Memory cell array circuit

ABSTRACT

A memory cell array includes a first column of memory cells, a second column of memory cells, a first bit line, a second bit line and a source line. The second column of memory cells is separated from the first column of memory cells in a first direction. The first column of memory cells and the second column of memory cells are arranged in a second direction. The first bit line is coupled to the first column of memory cells, and extends in the second direction. The second bit line is coupled to the second column of memory cells, and extends in the second direction. The source line extends in the second direction, is coupled to the first column of memory cells and the second column of memory cells.

PRIORITY CLAIM AND CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.62/673,786, filed May 18, 2018, which is herein incorporated byreference in its entirety.

BACKGROUND

The semiconductor integrated circuit (IC) industry has produced a widevariety of digital devices to address issues in a number of differentareas. Some of these digital devices, such as memory macros, areconfigured for the storage of data. As ICs have become smaller and morecomplex, the resistance of conductive lines within these digital devicesare also changed affecting the operating voltages of these digitaldevices and overall IC performance.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a circuit diagram of a memory cell, in accordance with someembodiments.

FIG. 2 is a block diagram of a memory cell array having a plurality ofmemory cells in FIG. 1, in accordance with some embodiments.

FIG. 3 is a schematic diagram of a memory circuit, in accordance withsome embodiments.

FIGS. 4A-4H are diagrams of a layout design, in accordance with someembodiments.

FIGS. 5A, 5B, 5C, 5D and 5E are cross-sectional views of a memorycircuit, in accordance with some embodiments.

FIG. 6 is a flowchart of a method of forming or manufacturing a memorycircuit in accordance with some embodiments.

FIG. 7 is a flowchart of a method of generating a layout design of amemory circuit in accordance with some embodiments.

FIG. 8 is a schematic view of a system for designing an IC layout designin accordance with some embodiments.

FIG. 9 is a block diagram of an IC manufacturing system, and an ICmanufacturing flow associated therewith, in accordance with at least oneembodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides different embodiments, or examples,for implementing features of the provided subject matter. Specificexamples of components, materials, values, steps, arrangements, or thelike, are described below to simplify the present disclosure. These are,of course, merely examples and are not limiting. Other components,materials, values, steps, arrangements, or the like, are contemplated.For example, the formation of a first feature over or on a secondfeature in the description that follows may include embodiments in whichthe first and second features are formed in direct contact, and may alsoinclude embodiments in which additional features may be formed betweenthe first and second features, such that the first and second featuresmay not be in direct contact. In addition, the present disclosure mayrepeat reference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In accordance with some embodiments, a memory cell array includes afirst column of memory cells, a second column of memory cells, a firstbit line, a second bit line and a source line. The second column ofmemory cells is separated from the first column of memory cells in afirst direction. The first column of memory cells and the second columnof memory cells are arranged in a second direction different from thefirst direction. The first bit line is coupled to the first column ofmemory cells, and extends in the second direction. The second bit lineis coupled to the second column of memory cells, and extends in thesecond direction. The source line extends in the second direction, iscoupled to the first column of memory cells and the second column ofmemory cells, and is shared by the first column of memory cells and thesecond column of memory cells.

In some embodiments, the source line includes a first conductive lineextending in the second direction, and being located on a first metallayer. In some embodiments, the source line further includes a secondconductive line and a set of vias. In some embodiments, the secondconductive line extends in the second direction, and is located on asecond metal layer above the first metal layer. In some embodiments, theset of vias electrically couple the first conductive line and the secondconductive line.

In some embodiments, a resistance of the first bit line or a resistanceof the second bit line is substantially equal to a resistance of thesource line.

In some embodiments, the first or second bit line includes a thirdconductive line extending in the second direction, and being located ona third metal layer. In some embodiments, the first or second bit linefurther includes a fourth conductive line and another set of vias. Insome embodiments, the fourth conductive line extends in the seconddirection, and is located on a fourth metal layer above the third metallayer. In some embodiments, the another set of vias electrically couplethe third conductive line and the fourth conductive line.

In some embodiments, memory cell array includes source lines SL sharedby adjacent columns of memory cells causing a decrease in the number ofsource lines and corresponding routing tracks than other approaches. Insome embodiments, by having less source lines and corresponding routingtracks, the width of source lines and corresponding routing tracks inthe memory cell array is increased resulting in less source lineresistance than other approaches. In some embodiments, by having lesssource line resistance, a difference between the source line resistanceand bit line resistance is smaller than other approaches. In someembodiments, by having a smaller difference between source lineresistance and bit line resistance than other approaches results insimpler peripheral circuitry for reading and writing to memory cellarray.

Memory Cell

FIG. 1 is a circuit diagram of a memory cell 100, in accordance withsome embodiments.

Memory cell 100 is a resistive random access memory (RRAM) cell used forillustration. Other types of memory are within the scope of variousembodiments. For example, in some embodiments, memory cell 102 includesa ferroelectric RAM (F-RAM), a Magnetoresistive RAM (MRAM), Phase-changememory (PCM), other forms of non-volatile RAM cells, or the like. Memorycell 100 is configured to store a logic “1” or a logic “0” based on theresistance the memory cell.

Memory cell 100 comprises a selector element (SE) 102 and a resistiveswitching element (RE) 104. In some embodiments, memory cell 100 isreferred to as a “1T1R” (one transistor, one resistor) architecture. Insome embodiments, memory cell 100 employs a number of transistors orresistive elements other than one.

Selector element 102 is an N-type metal oxide semiconductor (NMOS)transistor N1. In some embodiments, selector element 102 is a P-typemetal oxide semiconductor (PMOS) transistor. Other types of transistorsor numbers of transistors in selector element 102 are within thecontemplated scope of the present disclosure. In some embodiments,selector element 102 includes one or more diode elements or diodecoupled transistors. In some embodiments, selector element 102 includesone or more elements capable of exhibiting switching behavior orfunction.

A gate terminal of NMOS transistor N1 is coupled to a word line WL1, andis configured to receive a word line signal (not labelled). A drainterminal of NMOS transistor N1 is coupled with resistive switchingelement 104. A source terminal of NMOS transistor N1 is coupled to asource line SL1, and is configured to output/receive a source linesignal (not labelled) to/from the source line SL1. In some embodiments,the source terminal of NMOS transistor N1 is coupled to resistiveswitching element 104, and the drain terminal of NMOS transistor N1 iscoupled to the source line SL1.

Resistive switching element 104 includes a bottom electrode 104 a, aresistive switching material 104 b, and a top electrode 104 c. Resistiveswitching element 104 is configured to store a logic “1” or a logic “0”based on a variable resistance of the resistive switching material 104b. In some embodiments, the resistance of the resistive switchingmaterial 104 b is adjusted based on at least a voltage applied to theword line WL1, bit line BL1 or source line SL1.

Bottom electrode (BE) 104 a is coupled to the drain of NMOS transistorN1. Top electrode (TE) 104 c is coupled to the bit line BL1. BE 104 aand TE 104 c are conductive structures. In some embodiments, aconductive structure includes a metal, a metal compound or a dopedsemiconductor. In some embodiments, a metal includes at least Cu(Copper), Co, W, Ru, Al, or the like. In some embodiments, a metalcompound includes at least AlCu, W—TiN, TiSix, NiSix, TiN, TaN, or thelike. In some embodiments, a doped semiconductor includes at least dopedsilicon, or the like.

Resistive switching material 104 b is positioned between BE 104 a and TE104 c. In some embodiments, resistive switching material 104 b is adielectric material having one or more layers. In some embodiments,dielectric materials include one or more transition metal oxides (TMO).In some embodiments, TMOs include at least one selected from the groupconsisting of HfO_(x), TaO_(x), TiO_(x), AlO_(x), CuO_(x), NiO_(x),WO_(x), mixtures thereof, and alloys thereof. In some embodiments,dielectric materials include one or more binary oxides. In someembodiments, binary oxides include at least one selected from the groupconsisting of VO_(x), CrO_(x), MnO_(x), FeO_(x), CoO_(x), ZnO_(x),YO_(x), ZrO_(x), NbO_(x), MoO_(x), RuO_(x), AgO_(x), SiO_(x), CeO_(x),mixtures thereof, and alloys thereof. In some embodiments, dielectricmaterials include one or more ternary oxides. In some embodiments,ternary oxides include at least one selected from the group consistingof SrZrO_(x), SrTiO_(x), mixtures thereof, and alloys thereof. In someembodiments, dielectric materials include one or more quaternary oxides.In some embodiments, quaternary oxides include at least one selectedfrom the group consisting of Cd_(m)Ce_(n)Fe_(x)O_(y), mixtures thereof,and alloys thereof.

In some embodiments, the resistive switching material 104 b is changedfrom a low resistance state, known as a “Set,” to a high resistancestate, known as a “Reset,” and vice versa.

In some embodiments, the resistive switching material 104 b is “Set” byapplying at least a voltage to a corresponding word line WL1, bit lineBL1 or source line SL1 such that a filament or conduction path throughthe resistive switching material 104 b is formed or re-formed.

In some embodiments, the resistive switching material 104 b is “Reset”by applying at least a voltage to a corresponding word line WL1, bitline BL1 or source line SL1 such that the filament or conduction paththrough the resistive switching material 104 b is broken.

Memory Cell Array

FIG. 2 is a block diagram of a memory cell array 200 having a pluralityof memory cells in FIG. 1, in accordance with some embodiments. Forexample, memory cell 100 of FIG. 1 is usable as one or more memory cellsin memory cell array 200.

Memory cell array 200 comprises an array of memory cells 202[1,1],202[1,2], . . . , 202[2,2], . . . , 202[M,N] (collectively referred toas “array of memory cells 202A”) having M rows and N columns, where N isa positive integer corresponding to the number of columns in array ofmemory cells 202A and M is a positive integer corresponding to thenumber of rows in array of memory cells 202A. The rows of cells in arrayof memory cells 202A are arranged in a first direction X. The columns ofcells in array of memory cells 202A are arranged in a second directionY. The second direction Y is different from the first direction X. Insome embodiments, the second direction Y is perpendicular to the firstdirection X. Memory cell 100 of FIG. 1 is usable as one or more memorycells in array of memory cells 202A.

Each memory cell 202[1,1], 202[1,2], . . . , 202[2,2], . . . , 202[M,N]in array of memory cells 202A includes a corresponding resistiveswitching element RE1 coupled to a corresponding selector element SE1.Resistive switching element 104 of FIG. 1 is usable as one or moreresistive switching elements RE1 in memory cell array 200, and similardetailed description is therefore omitted. Selector element 102 of FIG.1 is usable as one or more selector elements SE1 in memory cell array200, and similar detailed description is therefore omitted.

Different types of memory cells in memory cell array 200 are within thecontemplated scope of the present disclosure. Different configurationsof array of memory cells 202A are within the contemplated scope of thepresent disclosure. Different configurations of bit lines BL, word linesWL or source lines SL in array of memory cells 202A are within thecontemplated scope of the present disclosure. Furthermore, in someembodiments, array of memory cells 202A includes multiple groups ofdifferent types of memory cell.

Memory cell array 200 further includes M word lines WL[1], . . . , WL[M](collectively referred to as “word line WL”). Each row 1, . . . , M inarray of memory cells 202A is associated with a corresponding word lineWL[1], . . . , WL[M]. Each word line WL extends in the first directionX. One or more of the word lines of the set of word lines WL in array ofmemory cells 202A corresponds to the word line WL1 of FIG. 1.

Memory cell array 200 further includes N bit lines BL[1], . . . , BL[N](collectively referred to as “bit line BL”). Each column 1, . . . , N inarray of memory cells 202A is associated with a corresponding bit lineBL[1], . . . , BL[N]. Each bit line BL extends in the second directionY. One or more bit lines of the set of bit lines BL in array of memorycells 202A corresponds to bit line BL1 of FIG. 1.

Memory cell array 200 further includes X source lines SL[1], . . . ,SL[X] (collectively referred to as “source line SL”), where X is apositive integer corresponding to the number of source lines. In someembodiments, for an even number of columns N in array of memory cells202A, integer X is equal to N/2. In some embodiments, for an odd numberof columns N in array of memory cells 202A, integer X is equal to(N+1)/2.

In some embodiments, each source line SL[1], . . . , SL[X] is positionedbetween a corresponding pair of bit lines BL[1], . . . , BL[N]. In someembodiments, adjacent columns of memory cells in array of memory cells202A are configured to share a single source line of the set of sourcelines SL. For example, source line SL1 is shared by columns 1 and 2 ofarray of memory cells 202A. Similarly, source line SL2 is shared bycolumns 2 and 3 of array of memory cells 202A. Similarly, source lineSLX is shared by columns N−1 and N of array of memory cells 202A.

Each source line SL extends in the second direction Y. One or moresource lines of the set of source lines SL in array of memory cells 202Acorresponds to source line SL1 of FIG. 1.

In some embodiments, a memory cell of array of memory cells 202A ispositioned between an adjacent bit line of bit lines BL and an adjacentsource line of source lines SL. For example, in row 1 and column 1 ofmemory cell array 200, memory cell 202[1,1] is positioned between bitline BL[1] and source line SL[1]. Similarly, in row 1 and column 2 ofmemory cell array 200, memory cell 202[1,2] is positioned between sourceline SL[1] and bit line BL[2].

Each resistive switching element RE1 is coupled between a correspondingbit line of bit lines BL and a corresponding drain terminal of acorresponding selector element SE1. Each gate terminal of acorresponding selector element SE1 is coupled to a corresponding wordline of word lines WL. Source terminals of a pair of adjacent selectorelement SE1 are coupled to a corresponding source line of source linesSL. In other words, source lines SL are shared amongst adjacent columnsof memory cells in memory cell array 200.

For example, resistive switching element RE1 of memory cell 202[1,1] iscoupled to bit line BL[1], the gate terminal of selector element SE1 ofmemory cell 202[1,1] is coupled to word line WL[1], and the sourceterminal of selector element SE1 of memory cell 202[1,1] is coupled tosource line SL1. Similarly, resistive switching element RE1 of memorycell 202[1,2] is coupled to bit line BL[2], the gate terminal ofselector element SE1 of memory cell 202[1,2] is coupled to word lineWL[1], and the source terminal of selector element SE1 of memory cell202[1,2] is coupled to source line SL1. Source line SL1 is shared byselector element SE1 of memory cell 202[1,1] and selector element SE1 ofmemory cell 202[1,2].

In some embodiments, memory cell array 200 includes source lines SLshared by adjacent columns of memory cells causing a decrease in thenumber of source lines and corresponding routing tracks than otherapproaches.

In some embodiments, by having less source lines and correspondingrouting tracks, the width of source lines and corresponding routingtracks in memory cell array 200 is increased resulting in less sourceline resistance than other approaches.

In some embodiments, by having less source line resistance, a differencebetween the source line resistance and bit line resistance is smallerthan other approaches. In some embodiments, by having a smallerdifference between source line resistance and bit line resistance thanother approaches results in simpler peripheral circuitry for reading andwriting to memory cell array 200.

In some embodiments, by memory cell array 200 or memory circuit 300(FIG. 3) or memory circuit 500 (FIGS. 5A-5E) having less source linesand corresponding routing tracks, memory cell array 200, memory circuit300 or memory circuit 500 occupies less area than other memory cellarrays or memory circuits. In some embodiments, by occupying less areathan other memory cell arrays, memory cell array 200, memory circuit 300or memory circuit 500 is denser and has a larger memory capacitycompared with other approaches.

Memory Circuit

FIG. 3 is a schematic diagram of a memory circuit 300, in accordancewith some embodiments. Memory circuit 300 is an embodiment of the blockdiagram of memory cell array 200 of FIG. 2 expressed in a schematicdiagram.

Memory circuit 300 relates to memory cell array 200 of FIG. 2. Memorycircuit 300 includes a memory cell array 302. Memory circuit 300 is aschematic representation of two adjacent columns and two adjacent rowsof a memory cell array 302. Memory cell array 302 is similar to memorycell array 200 of FIG. 2, and similar detailed description is thereforeomitted.

Memory cell array 302 includes memory cells 302[1,1], 302[1,2],302[2,1], and 302[2,2], bit lines BL1 and BL2, word lines WL1 and WL2,and a source line SL1.

Memory cells 302[1,1], 302[1,2], 302[2,1], and 302[2,2] are similar tocorresponding memory cells 202[1,1], 202[1,2], 202[2,1], and 202[2,2] ofFIG. 2, and similar detailed description is therefore omitted. Bit linesBL1 and BL2 are similar to corresponding bit lines BL[1] and BL[2] ofFIG. 2, and similar detailed description is therefore omitted. Wordlines WL1 and WL2 are similar to corresponding word lines WL[1] andWL[2] of FIG. 2, and similar detailed description is therefore omitted.Source line SL1 is similar to source line SL[1] of FIG. 2, and similardetailed description is therefore omitted.

Memory cells 302[1,1], 302[1,2], 302[2,1], and 302[2,2] includecorresponding selector elements 314 a, 314 b, 314 c and 314 d coupled tocorresponding resistive switching elements 350 a, 350 b, 350 c and 350d. Selector elements 314 a, 314 b, 314 c, and 314 d are similar toselector elements SE1 of FIG. 2, and similar detailed description istherefore omitted. Resistive switching elements 350 a, 350 b, 350 c, and350 d are similar to resistive switching elements RE1 of FIG. 2, andsimilar detailed description is therefore omitted.

Selector element 314 a is a transistor device with an active region 310and 2 gate portions 316 a and 316 b (e.g., fingers) of word line WL1. Insome embodiments, active region 310 of selector element 314 a or 314 bor active region 312 (described below) of selector element 314 c or 314d is referred to as an oxide definition (OD) region which defines thesource or drain diffusion regions of memory circuit 300. A source ofactive region 310 of selector element 314 a is coupled to the sourceline SL1. A drain of active region 310 of selector element 314 a iscoupled to resistive switching element 350 a by a conductive structure320 a and a conductive structure 330 a. Resistive switching element 350a is positioned between conductive structure 320 a and conductivestructure 340 a. Resistive switching element 350 a is coupled to bitline BL1 by the conductive structure 340 a.

Selector element 314 b is a transistor device with an active region 310and 2 gate portions 318 a and 318 b (e.g., fingers) of word line WL2. Asource of active region 310 of selector element 314 b is coupled to thesource line SL1. A drain of active region 310 of selector element 314 bis coupled to resistive switching element 350 b by a conductivestructure 320 b and a conductive structure 330 b. Resistive switchingelement 350 b is positioned between conductive structure 320 b andconductive structure 340 b. Resistive switching element 350 b is coupledto bit line BL1 by the conductive structure 340 b.

Selector element 314 c is a transistor device with an active region 312and 2 gate portions 316 a and 316 b (e.g., fingers) of word line WL1. Asource of active region 312 of selector element 314 c is coupled to thesource line SL1. A drain of active region 312 of selector element 314 cis coupled to resistive switching element 350 c by a conductivestructure 320 c and a conductive structure 330 c. Resistive switchingelement 350 c is positioned between conductive structure 320 c andconductive structure 340 c. Resistive switching element 350 c is coupledto bit line BL2 by the conductive structure 340 b.

Selector element 314 d is a transistor device with an active region 312and 2 gate portions 318 a and 318 b (e.g., fingers) of word line WL2. Asource of active region 312 of selector element 314 d is coupled to thesource line SL1. A drain of active region 312 of selector element 314 dis coupled to resistive switching element 350 d by a conductivestructure 320 d and a conductive structure 330 d. Resistive switchingelement 350 d is positioned between conductive structure 320 d andconductive structure 340 d. Resistive switching element 350 d is coupledto bit line BL2 by the conductive structure 340 d.

In some embodiments, at least word line WL1 or WL2 is in a polysilicon(POLY) layer of memory circuit 300.

The source line SL1 is coupled to the source of active region 310 ofselector elements 314 a and 314 b and the source of active region 312 ofselector elements 314 c and 314 d. In some embodiments, source line SL1is in a metal one (M1) layer of memory circuit 300. In some embodiments,source line SL1 is in the M1 layer and a metal two (M2) layer of memorycircuit 300. In some embodiments, at least conductive structure 330 a,330 b, 330 c or 330 d is in the M1 layer of memory circuit 300. In someembodiments, at least conductive structure 330 a, 330 b, 330 c or 330 dis in the M1 and M2 layer of memory circuit 300.

In some embodiments, at least conductive structure 320 a, 320 b, 320 cor 320 d is in a metal three (M3) layer of memory circuit 300.

In some embodiments, at least conductive structure 340 a, 340 b, 340 cor 340 d is in a metal four (M4) layer of memory circuit 300. In someembodiments, at least resistive switching element 350 a, 350 b, 350 c or350 d is between the M3 and the M4 layer of memory circuit 300.

In some embodiments, at least bit line BL1 or BL2 is in the M4 layer ofmemory circuit 300. In some embodiments, at least bit line BL1 or BL2 isin the M4 layer and a metal five (M5) layer of memory circuit 300.

In some embodiments, the POLY layer is below the M1 layer. In someembodiments, the M1 layer is below the M2 layer. In some embodiments,the M2 layer is below the M3 layer. In some embodiments, the M3 layer isbelow the M4 layer. In some embodiments, the M4 layer is below the M5layer. Other metal layers are within the scope of the presentdisclosure.

In some embodiments, memory circuit 300 also includes other circuits(e.g., other driver circuits, timing circuits, decoder circuits, etc.)that are not described for simplicity.

Layout Design of Memory Circuit

FIGS. 4A-4H are diagrams of a layout design 400, in accordance with someembodiments. Layout design 400 is a layout diagram of memory circuit 300of FIG. 3 or memory cell 100 of FIG. 1. Layout design 400 is usable tomanufacture memory cell 100, memory circuit 300 or 500.

FIG. 4A is a diagram of layout design 400. For ease of illustration,some of the labeled elements of FIGS. 4B-4H are not labelled in FIG. 4A.In some embodiments, FIGS. 4A-4H include additional elements not shownin FIGS. 4A-4H.

FIGS. 4B-4H are diagrams of a corresponding portion 400B-400H of layoutdesign 400 of FIG. 4A, simplified for ease of illustration. Portion 400Bincludes one or more features of layout design 400 of FIG. 4A from theactive (OD) level to the metal one (M1) level of layout design 400.Portion 400C includes one or more features of layout design 400 of FIG.4A from the M1 level to the M2 level of layout design 400. Portion 400Dincludes one or more features of layout design 400 of FIG. 4A from theM2 level to the M3 level of layout design 400. Portion 400E includes oneor more features of layout design 400 of FIG. 4A from the M3 level tothe TE level of layout design 400. Portion 400F includes one or morefeatures of layout design 400 of FIG. 4A from the M3 level to the M4level of layout design 400. Portion 400G includes one or more featuresof layout design 400 of FIG. 4A from the M4 level and via four (V4)level of layout design 400. Portion 400H includes one or more featuresof layout design 400 of FIG. 4A from the M5 level and V4 level of layoutdesign 400.

Layout design 400 includes one or more of memory cell layout patterns402[1,1], 402[1,2], 402[2,1] or 402[2,2]. Memory cell layout patterns402[1,1], 402[1,2], 402[2,1] and 402[2,2] are useable to manufacturecorresponding memory cells 302[1,1], 302[1,2], 302[2,1] and 302[2,2] ofmemory circuit 300 of FIG. 3.

In some embodiments, memory cell layout pattern 402[1,1], 402[1,2],402[2,1], 402[2,2] include at least a corresponding selector elementlayout pattern 404 a, 404 b, 404 c, 404 d and a corresponding resistiveswitching element layout pattern 450 a, 450 b, 450 c, 450 d (describedbelow.)

In some embodiments, selector element layout pattern 404 a includes atleast metal over diffusion layout patterns 420 a, 422 a, 422 b, gatelayout patterns 416 a, 416 b or active region layout pattern 410(described below.)

In some embodiments, selector element layout pattern 404 b includes atleast metal over diffusion layout patterns 420 b, 422 b, 422 c, gatelayout patterns 418 a, 418 b or active region layout pattern 410(described below.)

In some embodiments, selector element layout pattern 404 c includes atleast metal over diffusion layout patterns 420 c, 422 d, 422 e, gatelayout patterns 416 a, 416 b or active region layout pattern 412(described below.)

In some embodiments, selector element layout pattern 404 d includes atleast metal over diffusion layout patterns 420 d, 422 e, 422 f, gatelayout patterns 418 a, 418 b or active region layout pattern 412(described below.)

Layout design 400 includes active region layout patterns 410, 412(collectively referred to as a “set of active region layout patterns411”) extending in the second direction Y. Active region layout patterns410, 412 of the set of active region layout patterns 411 are separatedfrom one another in the first direction X. Active region layout patterns410, 412 are usable to manufacture corresponding active regions 310, 312of FIG. 3 or corresponding active regions 510, 512 (FIGS. 5A-5E) ofmemory circuit 500. In some embodiments, the set of active region layoutpatterns 411 is located on a first layout level. Other configurations orquantities of patterns in the set of active region layout patterns 411are within the scope of the present disclosure.

Active region layout pattern 410 is part of memory cell layout patterns402[1,1] and 402[1,2].

Layout design 400 further includes gate layout patterns 416 a, 416 b,418 a, 418 b (collectively referred to as a “set of gate layout patterns416”) each extending in the first direction X. Each of the layoutpatterns of the set of gate layout patterns 416 is separated from anadjacent layout pattern of the set of gate layout patterns 416 in thesecond direction Y by a first pitch.

Gate layout patterns 416 a, 416 b, 418 a, 418 b are usable tomanufacture corresponding gate portions 316 a, 316 b, 318 a, 318 b ofFIG. 3. Gate layout patterns 416 a, 416 b are usable to manufacturecorresponding gates 516 a, 516 b (FIGS. 5A-5E) of memory circuit 500.The set of gate layout patterns 416 are positioned on a second layoutlevel (POLY) different from the first layout level. The set of activeregion layout patterns 411 is below the set of gate layout patterns 416.

Gate layout pattern 416 a, 416 b, 418 a, 418 b is usable to manufacturethe gate terminal of NMOS transistor N1 of corresponding selectorelement 314 a, 314 b, 314 c, 314 d of FIG. 3. Other configurations orquantities of patterns in the set of gate layout patterns 416 are withinthe scope of the present disclosure.

Layout design 400 further includes metal over diffusion layout patterns420 a, 420 b, 420 c, 420 d (hereinafter referred to as a “set of metalover diffusion layout patterns 420”) and metal over diffusion layoutpatterns 422 a, 422 b, 422 c, 422 d, 422 e, 422 f (hereinafter referredto as a “set of metal over diffusion layout patterns 422”). In someembodiments, the set of metal over diffusion layout patterns 420 or 422extends in at least the first direction X or the second direction Y.

Each of the layout patterns of the set of metal over diffusion layoutpatterns 420 or 422 is separated from an adjacent layout pattern of theset of metal over diffusion layout patterns 420 or 422 in at least thefirst direction X or the second direction Y. The set of metal overdiffusion layout patterns is located on a third layout level. In someembodiments, the third layout level of layout design 400 is a metal overdiffusion (MD) level. In some embodiments, the MD level is positionedabove at least the active region of layout design 400.

In some embodiments, the set of metal over diffusion layout patterns 420or 422 includes one or more features of layout patterns located on a viaover diffusion (VD) level, a metal zero (M0) level or a via zero (V0)level of layout design 400 that is not shown for brevity. For example,in some embodiments, the third layout level may also include the M0level, the POLY level or the MD level of layout design 400. In someembodiments, the set of metal over diffusion layout patterns 420 or 422further includes via layout patterns useable to manufacture acorresponding set of vias that are coupled to upper metal layers (e.g.,conductive feature layout patterns 414 a, 414 b, 414 c, 414 d, 414 e).

The set of metal over diffusion layout patterns 420 or 422 is usable tomanufacture a corresponding set of contacts 520 or 522 (FIGS. 5A-5E) ofmemory circuit 500.

In some embodiments, metal over diffusion layout pattern 420 a is usableto manufacture at least a drain terminal of NMOS transistor N1 of memorycell 202[1,1] of FIG. 2 or memory cell 302[1,1] of FIG. 3. In someembodiments, metal over diffusion layout pattern 420 b is usable tomanufacture at least a drain terminal of NMOS transistor N1 of memorycell 202[2,1] of FIG. 2 or memory cell 302[2,1] of FIG. 3. In someembodiments, metal over diffusion layout pattern 420 c is usable tomanufacture at least a drain terminal of NMOS transistor N1 of memorycell 202[1,2] of FIG. 2 or memory cell 302[1,2] of FIG. 3. In someembodiments, metal over diffusion layout pattern 420 d is usable tomanufacture at least a drain terminal of NMOS transistor N1 of memorycell 202[2,2] of FIG. 2 or memory cell 302[2,2] of FIG. 3.

In some embodiments, metal over diffusion layout pattern 422 a or 422 bis usable to manufacture at least a source terminal of NMOS transistorN1 of memory cell 202[1,1] of FIG. 2 or memory cell 302[1,1] of FIG. 3.In some embodiments, metal over diffusion layout pattern 422 b or 422 cis usable to manufacture at least a source terminal of NMOS transistorN1 of memory cell 202[2,1] of FIG. 2 or memory cell 302[2,1] of FIG. 3.In some embodiments, metal over diffusion layout pattern 422 d or 422 eis usable to manufacture at least a source terminal of NMOS transistorN1 of memory cell 202[1,2] of FIG. 2 or memory cell 302[1,2] of FIG. 3.In some embodiments, metal over diffusion layout pattern 422 e or 422 fis usable to manufacture at least a source terminal of NMOS transistorN1 of memory cell 202[2,2] of FIG. 2 or memory cell 302[2,2] of FIG. 3.

Metal over diffusion layout patterns 420 a, 420 b, 422 a, 422 b, 422 care above active region layout pattern 410. Metal over diffusion layoutpatterns 420 c, 420 d, 422 d, 422 e, 422 f are above active regionlayout pattern 412. Other configurations or quantities of patterns inthe set of metal over diffusion layout patterns 420 or 422 are withinthe scope of the present disclosure.

Layout design 400 further includes conductive feature layout patterns414 a, 414 b, 414 c, 414 d, 414 e (hereinafter referred to as a “set ofconductive feature layout patterns 414”) extending in the seconddirection Y. In some embodiments, the set of conductive feature layoutpatterns 414 extends in two directions (e.g., first direction X orsecond direction Y). The set of conductive feature layout patterns 414includes one or more conductive feature layout patterns. The set ofconductive feature layout patterns 414 is located on a fourth layoutlevel. In some embodiments, the fourth layout level of layout design 400is metal one (M1). In some embodiments, the M1 level is positioned aboveat least the active region, the M0 level, the POLY level or the MD levelof layout design 400.

The set of conductive feature layout patterns 414 is usable tomanufacture a corresponding set of conductive structures 514 (FIGS.5A-5E) of memory circuit 500. Conductive feature layout patterns 414 a,414 b, 414 c, 414 d are usable to manufacture corresponding conductivestructures 330 a, 330 b, 330 c, 330 d of FIG. 3. Conductive featurelayout pattern 414 e is usable to manufacture source line SL1 of FIG. 3or conductive structure 514 e (FIGS. 5A-5E) of memory circuit 500.

Conductive feature layout patterns 414 a, 414 c overlap gate layoutpatterns 416 a, 416 b. Conductive feature layout patterns 414 b, 414 doverlap gate layout patterns 418 a, 418 b. Conductive feature layoutpattern 414 e overlaps gate layout patterns 416 a, 416 b, 418 a, 418 band active region layout patterns 410, 412.

Conductive feature layout patterns 414 a, 414 c overlap correspondingmetal over diffusion layout patterns 420 a, 420 c. Conductive featurelayout patterns 414 b, 414 d overlap corresponding metal over diffusionlayout patterns 420 b, 420 d. Conductive feature layout pattern 414 eoverlaps metal over diffusion layout patterns 422 a, 422 b, 422 c, 422d, 422 e, 422 f.

Conductive feature layout patterns 414 a, 414 b are located above anedge of active region layout pattern 410 associated with correspondingdrain regions of NMOS transistor N1 of corresponding selector element314 a, 314 b of FIG. 3. Conductive feature layout patterns 414 c, 414 dare located above an edge of active region layout pattern 412 associatedwith corresponding drain regions of NMOS transistor N1 of correspondingselector element 314 c, 314 d of FIG. 3. Conductive feature layoutpattern 414 e is located above an edge of active region layout patterns410 and 412 associated with source regions of NMOS transistor N1 ofcorresponding selector element 314 a, 314 b, 314 c, 314 d of FIG. 3.

Other configurations or quantities of patterns in the set of conductivefeature layout patterns 414 are within the scope of the presentdisclosure.

Layout design 400 further includes conductive feature layout patterns424 a, 424 b, 424 c, 424 d, 424 e (hereinafter referred to as a “set ofconductive feature layout patterns 424”) extending in the seconddirection Y. In some embodiments, the set of conductive feature layoutpatterns 424 extends in two directions (e.g., first direction X orsecond direction Y). The set of conductive feature layout patterns 424includes one or more conductive feature layout patterns. The set ofconductive feature layout patterns 424 is located on a fifth layoutlevel. In some embodiments, the fifth layout level of layout design 400is metal two (M2). In some embodiments, the M2 level is positioned aboveat least the active region, the M0 level, the POLY level, the MD levelor the M1 level of layout design 400.

The set of conductive feature layout patterns 424 is usable tomanufacture a corresponding set of conductive structures 524 (FIGS.5A-5E) of memory circuit 500. In some embodiments, conductive featurelayout patterns 424 a, 424 b, 424 c, 424 d are usable to manufacturecorresponding conductive structures 330 a, 330 b, 330 c, 330 d of FIG.3. Conductive feature layout pattern 424 e is usable to manufacturesource line SL1 of FIG. 3 or conductive structure 524 e (FIGS. 5A-5E) ofmemory circuit 500. In some embodiments, source line SL1 of FIG. 3 ormemory circuit 500 of FIGS. 5A-5E includes conductive structures 514 e,524 e located on two different metal levels, and is manufactured bycorresponding conductive feature layout patterns 414 e, 424 e.

Conductive feature layout patterns 424 a, 424 b, 424 c, 424 d, 424 e areabove corresponding conductive feature layout patterns 414 a, 414 b, 414c, 414 d, 414 e. In some embodiments, an edge of at least conductivefeature layout pattern 424 a, 424 b, 424 c, 424 d or 424 e is aligned inat least the first direction X or the second direction Y with an edge ofa corresponding conductive feature layout pattern 414 a, 414 b, 414 c,414 d or 414 e.

Conductive feature layout patterns 424 a, 424 c overlap gate layoutpatterns 416 a, 416 b. Conductive feature layout patterns 424 b, 424 doverlap gate layout patterns 418 a, 418 b. Conductive feature layoutpattern 424 e overlaps gate layout patterns 416 a, 416 b, 418 a, 418 band active region layout patterns 410, 412.

Conductive feature layout patterns 424 a, 424 c overlap correspondingmetal over diffusion layout patterns 420 a, 420 c. Conductive featurelayout patterns 424 b, 424 d overlap corresponding metal over diffusionlayout patterns 420 b, 420 d. Conductive feature layout pattern 424 eoverlaps metal over diffusion layout patterns 422 a, 422 b, 422 c, 422d, 422 e, 422 f.

Conductive feature layout patterns 424 a, 424 b are located above anedge of active region layout pattern 410 associated with correspondingdrain regions of NMOS transistor N1 of corresponding selector element314 a, 314 b of FIG. 3. Conductive feature layout patterns 424 c, 424 dare located above an edge of active region layout pattern 412 associatedwith corresponding drain regions of NMOS transistor N1 of correspondingselector element 314 c, 314 d of FIG. 3. Conductive feature layoutpattern 424 e is located above an edge of active region layout patterns410 and 412 associated with source regions of NMOS transistor N1 ofcorresponding selector element 314 a, 314 b, 314 c, 314 d of FIG. 3.

Other configurations or quantities of patterns in the set of conductivefeature layout patterns 424 are within the scope of the presentdisclosure.

Layout design 400 further includes via layout patterns 430 a, 430 b, 430c, 430 d (collectively referred to as a “set of via layout patterns430”) and via layout patterns 432 a, 432 b, 432 c, 432 d, 432 e, 432 f(collectively referred to as a “set of via layout patterns 432”).

Set of via layout patterns 430 or 432 are between the set of conductivefeature layout patterns 424 and the set of conductive feature layoutpatterns 414.

Via layout patterns 430 a, 430 b, 430 c, 430 d of the set of via layoutpatterns 430 are between corresponding conductive feature layoutpatterns 424 a, 424 b, 424 c, 424 d of the set of conductive featurepatterns 424 and corresponding conductive feature layout patterns 414 a,414 b, 414 c, 414 d of the set of conductive feature patterns 414.

Via layout patterns 432 a, 432 b, 432 c, 432 d, 432 e, 432 f of the setof via layout patterns 432 are between conductive feature layout pattern424 e of the set of conductive feature patterns 424 and conductivefeature layout pattern 414 e of the set of conductive feature patterns414.

The set of via layout patterns 430 and 432 are positioned at a V1 levelof layout design 400. In some embodiments, the V1 level is between theM1 level and the M2 level. In some embodiments, the V1 level ispositioned above at least the V0 level, the VG level or the VD level oflayout design 400.

The set of via layout patterns 430 is usable to manufacture acorresponding set of vias 530 (FIGS. 5A-5E). The set of vias 530 coupleat least a member of the set of conductive structures 524 to at least amember of the set of conductive structures 514.

The set of via layout patterns 432 is usable to manufacture acorresponding set of vias 532 (FIGS. 5A-5E). The set of vias 532 coupleat least a member of the set of conductive structures 524 to at least amember of the set of conductive structures 514.

In some embodiments, a via layout pattern 430 a, 430 b, 430 c, 430 d ofthe set of via layout patterns 430 is located where a correspondingconductive feature layout pattern 424 a, 424 b, 424 c, 424 d of the setof conductive feature layout patterns 424 overlaps a correspondinglayout pattern 420 a, 420 b, 420 c, 420 d of the set of metal overdiffusion layout patterns 420. In some embodiments, a center of vialayout pattern 430 a, 430 b, 430 c, 430 d of the set of via layoutpatterns 430 is below a center of a corresponding conductive featurelayout pattern 424 a, 424 b, 424 c, 424 d of the set of conductivefeature layout patterns 424.

In some embodiments, a center of via layout pattern 430 a, 430 b, 430 c,430 d of the set of via layout patterns 430 is aligned in at least thefirst direction X or the second direction Y with a center of acorresponding layout pattern 420 a, 420 b, 420 c, 420 d of the set ofmetal over diffusion layout patterns 420 resulting in a source line,manufactured by layout design 400, with a lower source line resistancethan other approaches.

In some embodiments, a via layout pattern 432 a, 432 b, 432 c, 432 d,432 e, 432 f of the set of via layout patterns 432 is located whereconductive feature layout pattern 424 e of the set of conductive featurelayout patterns 424 overlaps a corresponding layout pattern 422 a, 422b, 422 c, 422 d, 422 e, 422 f of the set of metal over diffusion layoutpatterns 422. In some embodiments, a center of via layout pattern 432 a,432 b, 432 c, 432 d, 432 e, 432 f of the set of via layout patterns 432is aligned in at least the first direction X or the second direction Ywith a center of a corresponding layout pattern 422 a, 422 b, 422 c, 422d, 422 e, 422 f of the set of metal over diffusion layout patterns 422resulting in a source line, manufactured by layout design 400, with alower source line resistance than other approaches.

Other configurations of set of via layout patterns 430 or 432 are withinthe scope of the present disclosure.

Layout design 400 further includes conductive feature layout patterns434 a, 434 b, 434 c, 434 d (hereinafter referred to as a “set ofconductive feature layout patterns 434”) and conductive feature layoutpatterns 436 a, 436 b, 436 c (hereinafter referred to as a “set ofconductive feature layout patterns 436”).

The set of conductive feature layout patterns 436 extends in the seconddirection Y. In some embodiments, the set of conductive feature layoutpatterns 434 extends in at least the first direction X or the seconddirection Y. In some embodiments, at least one layout pattern of the setof conductive feature layout patterns 434 has a rectangular shape.

The set of conductive feature layout patterns 434 or 436 includes one ormore conductive feature layout patterns. The set of conductive featurelayout patterns 434 or 436 is located on a sixth layout level. In someembodiments, the sixth layout level of layout design 400 is metal three(M3). In some embodiments, the M3 level is positioned above at least theactive region, the M0 level, the POLY level, the MD level, the M1 levelor the M2 level of layout design 400.

The set of conductive feature layout patterns 434 is usable tomanufacture a corresponding set of conductive structures 534 (FIGS.5A-5E) of memory circuit 500. In some embodiments, conductive featurelayout patterns 434 a, 434 b, 434 c, 434 d are usable to manufacturecorresponding conductive structures 320 a, 320 b, 320 c, 320 d of FIG.3.

Conductive feature layout patterns 436 a, 436 b are usable tomanufacture corresponding conductive structures 536 a, 536 b (FIGS.5A-5E) of memory circuit 500 configured as corresponding word lines WL1,WL2.

Conductive feature layout patterns 434 a, 434 b, 434 c, 434 d are abovecorresponding conductive feature layout patterns 424 a, 424 b, 424 c,424 d. The set of conductive feature layout patterns 434 or 436 overlapat least a portion of one or more of conductive feature layout patterns424 a, 424 b, 424 c, 424 d or 424 e. Conductive feature layout patterns436 b is positioned between conductive feature layout patterns 434 a,434 b, 434 c, 434 d.

Other configurations or quantities of patterns in the set of conductivefeature layout patterns 434 or 436 are within the scope of the presentdisclosure.

Layout design 400 further includes via layout patterns 438 a, 438 b, 438c, 438 d (collectively referred to as a “set of via layout patterns438”) between the set of conductive feature layout patterns 424 and theset of conductive feature layout patterns 434.

Via layout patterns 438 a, 438 b, 438 c, 438 d of the set of via layoutpatterns 438 are between corresponding conductive feature layoutpatterns 424 a, 424 b, 424 c, 424 d of the set of conductive featurepatterns 424 and corresponding conductive feature layout patterns 434 a,434 b, 434 c, 434 d of the set of conductive feature patterns 434.

The set of via layout patterns 438 are positioned at a V2 level oflayout design 400. In some embodiments, the V2 level is between the M2level and the M3 level. In some embodiments, the V2 level is positionedabove at least the V0 level, the VG level, the VD level or the V1 levelof layout design 400.

The set of via layout patterns 438 is usable to manufacture acorresponding set of vias 538 (FIGS. 5A-5E). The set of vias 538 coupleat least a member of the set of conductive structures 524 to at least amember of the set of conductive structures 534.

In some embodiments, a via layout pattern 438 a, 438 b, 438 c, 438 d ofthe set of via layout patterns 438 is located where a correspondingconductive feature layout pattern 424 a, 424 b, 424 c, 424 d of the setof conductive feature layout patterns 424 is overlapped by acorresponding layout pattern 434 a, 434 b, 434 c, 434 d of the set ofconductive feature layout patterns 434.

In some embodiments, a center of via layout pattern 438 a, 438 b, 438 c,438 d of the set of via layout patterns 438 is aligned in at least thefirst direction X or the second direction Y with a center of acorresponding via layout pattern 430 a, 430 b, 430 c, 430 d of the setof via layout patterns 430.

Other configurations of set of via layout patterns 438 is within thescope of the present disclosure.

Layout design 400 further includes resistive switching element layoutpatterns 450 a, 450 b, 450 c, 450 d (hereinafter referred to as a “setof resistive switching element layout patterns 450”.)

The set of resistive switching element layout patterns 450 are usable tomanufacture set of resistive switching elements 350 or set of resistiveswitching elements 550 (FIGS. 5A-5E) of memory circuit 500. In someembodiments, resistive switching element layout patterns 450 a, 450 b,450 c, 450 d are usable to manufacture corresponding resistive switchingelements 350 a, 350 b, 350 c, 350 d of FIG. 3. At least one of the setof resistive switching element layout patterns 450 is usable tomanufacture resistive switching element 104 of FIG. 1.

The set of resistive switching element layout patterns 450 is located ona seventh layout level. In some embodiments, the seventh layout level oflayout design 400 is above the M3 and below the M4 level. In someembodiments, the seventh layout level is positioned above at least theactive region, the M0 level, the POLY level, the MD level, the M1 level,the M2 level or the M3 level of layout design 400.

Resistive switching element layout patterns 450 a, 450 b, 450 c, 450 dinclude corresponding bottom electrode layout patterns 452 a, 452 b, 452c, 452 d (hereinafter referred to as a “set of bottom electrode layoutpatterns 452”), corresponding resistive switching material layoutpatterns 454 a, 454 b, 454 c, 454 d (hereinafter referred to as a “setof resistive switching material layout patterns 454”) and correspondingtop electrode layout patterns 460 a, 460 b, 460 c, 460 d (hereinafterreferred to as a “set of top electrode layout patterns 460.”)

The set of bottom electrode layout patterns 452 are usable tomanufacture a bottom electrode 104 a of FIG. 1 or a set of bottomelectrodes 552 (FIGS. 5A-5E) of memory circuit 500.

The set of bottom electrode layout patterns 452 extends in at least thefirst direction X or the second direction Y. In some embodiments, atleast one layout pattern of the set of bottom electrode layout patterns452 has a rectangular shape. The set of bottom electrode layout patterns452 includes one or more bottom electrode layout patterns.

Bottom electrode layout patterns 452 a, 452 b, 452 c, 452 d are abovecorresponding conductive feature layout patterns 434 a, 434 b, 434 c,434 d. In some embodiments, a center of bottom electrode layout pattern452 a, 452 b, 452 c, 452 d of the set of bottom electrode layoutpatterns 452 is aligned in at least the first direction X or the seconddirection Y with a center of a corresponding conductive feature layoutpattern 434 a, 434 b, 434 c, 434 d of the set of conductive featurelayout patterns 434.

The set of resistive switching material layout patterns 454 are usableto manufacture a resistive switching material 104 b of FIG. 1 or aresistive switching material 554 (FIGS. 5A-5E) of memory circuit 500.

The set of resistive switching material layout patterns 454 extends inthe second direction Y. In some embodiments, at least one layout patternof the set of resistive switching material layout patterns 454 has arectangular shape. The set of resistive switching material layoutpatterns 454 includes one or more resistive switching material layoutpatterns.

Resistive switching material layout patterns 454 a, 454 b, 454 c, 454 doverlap at least a portion of corresponding conductive feature layoutpatterns 434 a, 434 b, 434 c, 434 d. Resistive switching material layoutpatterns 454 a, 454 b, 454 c, 454 d overlap corresponding bottomelectrode layout patterns 452 a, 452 b, 452 c, 452 d. Resistiveswitching material layout patterns 454 a, 454 b, 454 c, 454 d are abovecorresponding bottom electrode layout patterns 452 a, 452 b, 452 c, 452d.

The set of top electrode layout patterns 460 are usable to manufacture atop electrode 104 c of FIG. 1 or a set of top electrodes 560 (FIGS.5A-5E) of memory circuit 500.

The set of top electrode layout patterns 460 extends in at least thefirst direction X or the second direction Y. In some embodiments, atleast one layout pattern of the set of top electrode layout patterns 460has a rectangular shape. The set of top electrode layout patterns 460includes one or more top electrode layout patterns.

Top electrode layout patterns 460 a, 460 b, 460 c, 460 d are abovecorresponding resistive switching material layout patterns 454 a, 454 b,454 c, 454 d. In some embodiments, a center of top electrode layoutpattern 460 a, 460 b, 460 c, 460 d of the set of top electrode layoutpatterns 460 is offset in at least the second direction Y with a centerof a corresponding bottom electrode layout pattern 452 a, 452 b, 452 c,452 d of the set of bottom electrode layout patterns 452.

Other configurations or quantities of patterns in the set of resistiveswitching element layout patterns 450, set of bottom electrode layoutpatterns 452, set of resistive switching material layout patterns 454,set of top electrode layout patterns 460 are within the scope of thepresent disclosure.

Layout design 400 further includes conductive feature layout patterns440 a, 440 b (hereinafter referred to as a “set of conductive featurelayout patterns 440”) extending in the second direction Y. The set ofconductive feature layout patterns 440 includes one or more conductivefeature layout patterns. The set of conductive feature layout patterns440 is located on an eighth layout level. In some embodiments, theeighth layout level of layout design 400 is metal four (M4). In someembodiments, the M4 level is positioned above at least the activeregion, the M0 level, the POLY level, the MD level, the M1 level, the M2level or the M3 level of layout design 400.

The set of conductive feature layout patterns 440 is usable tomanufacture set of conductive structures 540 (FIGS. 5A-5E) of memorycircuit 500. In some embodiments, conductive feature layout patterns 440a, 440 b are usable to manufacture corresponding conductive structures540 a, 540 b (FIGS. 5A-5E) of memory circuit 500. In some embodiments,conductive feature layout pattern 440 a is usable to manufactureconductive structures 340 a, 340 b of FIG. 3. In some embodiments,conductive feature layout pattern 440 b is usable to manufactureconductive structures 340 c, 340 d of FIG. 3. In some embodiments,conductive feature layout patterns 440 a, 440 b are usable tomanufacture corresponding bit lines BL1, BL2 of FIG. 3.

Conductive feature layout patterns 440 a, 440 b are above resistiveswitching element layout patterns 450 a, 450 b, 450 c, 450 d. Conductivefeature layout pattern 440 a overlaps resistive switching element layoutpatterns 450 a, 450 b. Conductive feature layout pattern 440 b overlapsresistive switching element layout patterns 450 c, 450 d. In someembodiments, a center of conductive feature layout patterns 440 a, 440 bis aligned in at least the first direction X with a center ofcorresponding resistive switching element layout patterns 450 a, 450 b.

Other configurations or quantities of patterns in the set of conductivefeature layout patterns 440 are within the scope of the presentdisclosure.

Layout design 400 further includes conductive feature layout patterns470 a, 470 b (hereinafter referred to as a “set of conductive featurelayout patterns 470”) extending in the second direction Y. The set ofconductive feature layout patterns 470 includes one or more conductivefeature layout patterns. The set of conductive feature layout patterns470 is located on a ninth layout level. In some embodiments, the ninthlayout level of layout design 400 is metal five (M5). In someembodiments, the M5 level is positioned above at least the activeregion, the M0 level, the POLY level, the MD level, the M1 level, the M2level, the M3 or the M4 level of layout design 400.

The set of conductive feature layout patterns 470 is usable tomanufacture set of conductive structures 570 (FIGS. 5A-5E) of memorycircuit 500. In some embodiments, conductive feature layout patterns 470a, 470 b are usable to manufacture corresponding conductive structures570 a, 570 b (FIGS. 5A-5E) of memory circuit 500. In some embodiments,conductive feature layout patterns 470 a, 470 b are usable tomanufacture corresponding bit lines BL1, BL2 of FIG. 3 or correspondingconductive structures 570 a, 570 b (FIGS. 5A-5E) of memory circuit 500.In some embodiments, bit line BL1 of FIG. 3 or memory circuit 500 ofFIGS. 5A-5E includes conductive structures 540 a, 570 a located on twodifferent metal levels, and is manufactured by corresponding conductivefeature layout patterns 440 a, 470 a. In some embodiments, bit line BL2of FIG. 3 or memory circuit 500 of FIGS. 5A-5E includes conductivestructures 540 b, 570 b located on two different metal levels, and ismanufactured by corresponding conductive feature layout patterns 440 b,470 b.

Conductive feature layout patterns 470 a, 470 b are above conductivefeature layout patterns 440 a, 440 b. In some embodiments, an edge of atleast conductive feature layout pattern 470 a, 470 b is aligned in atleast the first direction X or the second direction Y with an edge of acorresponding conductive feature layout pattern 440 a, 440 b. In someembodiments, a center of conductive feature layout patterns 470 a, 470 bis aligned in at least the first direction X or the second direction Ywith a center of corresponding conductive feature layout pattern 440 a,440 b.

Other configurations or quantities of patterns in the set of conductivefeature layout patterns 470 are within the scope of the presentdisclosure.

Layout design 400 further includes via layout patterns 472 a, 472 b, 472c, 472 d, 472 e, 472 f, 472 g, 472 h (collectively referred to as a “setof via layout patterns 472”) between the set of conductive featurelayout patterns 470 and the set of conductive feature layout patterns440.

Via layout patterns 472 a, 472 b, 472 c, 472 d of the set of via layoutpatterns 472 are between conductive feature layout pattern 470 a of theset of conductive feature patterns 470 and conductive feature layoutpattern 440 a of the set of conductive feature patterns 440.

Via layout patterns 472 e, 472 f, 472 g, 472 h of the set of via layoutpatterns 472 are between conductive feature layout pattern 470 b of theset of conductive feature patterns 470 and conductive feature layoutpattern 440 b of the set of conductive feature patterns 440.

The set of via layout patterns 472 are positioned at a V4 level oflayout design 400. In some embodiments, the V4 level is between the M4level and the M5 level. In some embodiments, the V4 level is positionedabove at least the V0 level, the VG level, the VD level, the V1 level orthe V2 level of layout design 400.

The set of via layout patterns 472 is usable to manufacture acorresponding set of vias 572 (FIGS. 5A-5E). The set of vias 572 coupleat least a member of the set of conductive structures 570 to at least amember of the set of conductive structures 540.

In some embodiments, a center of at least one via layout pattern 472 a,472 b, 472 c or 472 d of the set of via layout patterns 472 is alignedin at least the first direction X with a center of a layout pattern 450a or 450 b of the set of resistive switching element layout patterns450. In some embodiments, a center of at least one via layout pattern472 e, 472 f, 472 g or 472 h of the set of via layout patterns 472 isaligned in at least the first direction X with a center of a layoutpattern 450 c or 450 d of the set of resistive switching element layoutpatterns 450.

Other configurations of set of via layout patterns 472 is within thescope of the present disclosure.

FIGS. 5A, 5B, 5C, 5D and 5E are cross-sectional views of a memorycircuit 500, in accordance with some embodiments. FIG. 5A is across-sectional view of a memory circuit 500 corresponding to layoutdesign 400 as intersected by plane A-A′, FIG. 5B is a cross-sectionalview of a memory circuit 500 corresponding to layout design 400 asintersected by plane B-B′, FIG. 5C is a cross-sectional view of a memorycircuit 500 corresponding to layout design 400 as intersected by planeC-C′, and FIG. 5D is a cross-sectional view of a memory circuit 500corresponding to layout design 400 as intersected by plane D-D′, inaccordance with some embodiments. FIG. 5E is a cross-sectional view of azoomed in portion of resistive switching element 550 a or 550 c ofmemory circuit 500, in accordance with some embodiments. Memory circuit500 is manufactured by layout design 400.

Components that are the same or similar to those in one or more of FIGS.1-3 and 5A-5E (shown below) are given the same reference numbers, anddetailed description thereof is thus omitted.

Memory circuit 500 is manufactured by layout design 400. Structuralrelationships including alignment, lengths and widths, as well asconfigurations of memory circuit 500 of FIGS. 5A-5E are similar to thestructural relationships and configurations of memory circuit 300 ofFIG. 3 or layout design 400 of FIGS. 4A-4H, and will not be described ineach of FIGS. 3, 4A-4H and 5A-5E for brevity.

Memory circuit 500 relates to memory circuit 300 of FIG. 3, and similardetailed description is therefore omitted. For example, memory circuit500 is an implementation of portions of memory cells 302[1,1] and302[1,2]. In some embodiments, memory circuit 500 is portions of columns1 and 2 of memory cells 302[1,1] and 302[1,2].

Memory circuit 500 includes memory cells 502 a and 502 b which aresimilar to memory cells 302[1,1] and 302[1,2] of FIG. 3, and similardetailed description is therefore omitted. In some embodiments, memorycell 502 a includes at least active region 510, contact 520 a, gate 516a, gate 516 b, contact 522 a or contact 522 b (described below.) In someembodiments, memory cell 502 b includes at least active region 512,contact 520 c, gate 516 a, gate 516 b or contact 522 d (describedbelow.) In some embodiments, memory circuit 500 further includesadditional memory cells or features consistent with the descriptions ofFIG. 3 or FIGS. 4A-4H.

Memory circuit 500 includes one or more active regions 510, 512(collectively referred to as “set of active regions 511”) in a substrate(not shown). The set of active regions 511 extends in the seconddirection Y and is located on a first level of memory circuit 500. Eachactive region of the set of active regions 511 is separated from eachother in the first direction X. In some embodiments, set of activeregions 511 of memory circuit 500 is referred to as an oxide definition(OD) region which defines the source or drain diffusion regions ofmemory circuit 500. In some embodiments, the first level of memorycircuit 500 is referred to as the Active/Fin level. In some embodiments,active region 510, 512 includes a set of fins (not shown) extending inthe first direction and being below a set of gates 516. In someembodiments, each of the fins (not shown) is separated from an adjacentfin of the set of fins (not shown) by a fin pitch (not shown). Otherquantities or configurations of the set of active region 511 are withinthe scope of the present disclosure.

Memory circuit 500 further includes one or more gates 516 a, 516 b(collectively referred to as “set of gates 516”) extending in the firstdirection X, overlapping at least the set of active regions 511 andbeing located on a second level of memory circuit 500. In someembodiments, the second level of memory circuit 500 is different fromthe first level. In some embodiments, the second level is the POLYlevel. Each of the gates of the set of gates 516 is separated from anadjacent gate of the set of gates 516 in the second direction Y by apoly pitch. In some embodiments, the second level of memory circuit 500is referred to as the Poly level.

Gates 516 a, 516 b correspond to the gate terminal of NMOS transistor N1of selector element 314 a or 314 c of FIG. 3. Other quantities orconfigurations of the set of gates 516 are within the scope of thepresent disclosure.

Memory circuit 500 further includes one or more contacts 520 a, 520 c(collectively referred to as a “set of contacts 520”) and contacts 522a, 522 b, 522 d (collectively referred to as a “set of contacts 522”)extending in at least the first direction X or the second direction Y,overlapping the set of active regions 511, and being located on a thirdlevel of memory circuit 500. In some embodiments, the third level ofmemory circuit 500 is the MD level. In some embodiments, the MD level ispositioned above at least the active region of layout design 400. Insome embodiments, the set of contacts 520 or 522 further includes viasthat are configured to be coupled to upper metal layers (e.g., M1, M2,etc.)

Each of the contacts 520 a, 520 c of the set of contacts 520 isseparated from an adjacent contact of the set of contacts 520 in atleast the first direction X or the second direction Y. Each of thecontacts 522 a, 522 b, 522 d of the set of contacts 522 is separatedfrom an adjacent contact of the set of contacts 522 in at least thefirst direction X or the second direction Y.

In some embodiments, contact 520 a is a drain terminal of NMOStransistor N1 of memory cell 202[1,1] of FIG. 2 or memory cell 302[1,1]of FIG. 3. In some embodiments, contact 520 c is a drain terminal ofNMOS transistor N1 of memory cell 202[1,2] of FIG. 2 or memory cell302[1,2] of FIG. 3.

In some embodiments, contact 522 a or 522 b is at least a sourceterminal of NMOS transistor N1 of memory cell 202[1,1] of FIG. 2 ormemory cell 302[1,1] of FIG. 3. In some embodiments, contact 522 d is atleast a source terminal of NMOS transistor N1 of memory cell 202[1,2] ofFIG. 2 or memory cell 302[1,2] of FIG. 3.

Other quantities or configurations of the set of contacts 520 or 522 arewithin the scope of the present disclosure.

Memory circuit 500 further includes one or more conductive structures514 a, 514 c, 514 e (collectively referred to as a “set of conductivestructures 514”) extending in at least the first direction X or thesecond direction Y. The set of conductive structures 514 is located on afourth level. In some embodiments, the fourth level of memory circuit500 is metal one (M1). In some embodiments, the M1 level is positionedabove at least the active region, the M0 level, the POLY level or the MDlevel of memory circuit 500.

Conductive structures 514 a, 514 c are corresponding conductivestructures 330 a, 330 c of FIG. 3. Conductive structure 514 e is sourceline SL1 of FIG. 3 or source line SL1 of FIG. 1.

In some embodiments, conductive structure 514 a is electrically coupledto at least a drain terminal of NMOS transistor N1 of memory circuit500, memory cell 202[1,1] of FIG. 2 or memory cell 302[1,1] of FIG. 3 bycontact 520 a.

In some embodiments, conductive structure 514 c is electrically coupledto at least a drain terminal of NMOS transistor N1 of memory circuit500, memory cell 202[1,2] of FIG. 2 or memory cell 302[1,2] of FIG. 3 byat least contact 520 c.

In some embodiments, conductive structure 514 e is electrically coupledto at least a source terminal of NMOS transistor N1 of memory circuit500, memory cell 202[1,1] of FIG. 2 or memory cell 302[1,1] of FIG. 3 byat least contact 522 a.

In some embodiments, conductive structure 514 e is electrically coupledto at least a source terminal of NMOS transistor N1 of memory circuit500, memory cell 202[1,2] of FIG. 2 or memory cell 302[1,2] of FIG. 3 byat least contact 522 d.

Other quantities or configurations of the set of conductive structures514 are within the scope of the present disclosure.

Memory circuit 500 further includes one or more vias 530 a, 530 c(collectively referred to as a “set of vias 530”) and vias 532 a, 532 b,532 d (collectively referred to as a “set of vias 532”). In someembodiments, set of vias 530 or 532 electrically couple the set ofconductive structures 514 to upper metal layers (e.g., M2). In someembodiments, set of vias 530 or 532 is in the V1 level of memory circuit500. The V1 level of memory circuit 500 is between the fourth level anda fifth level of memory circuit 500. Other quantities or configurationsof the set of vias 530 or 532 are within the scope of the presentdisclosure.

Memory circuit 500 further includes one or more conductive structures524 a, 524 c, 524 e (collectively referred to as a “set of conductivestructures 524”) extending in at least the first direction X or thesecond direction Y. The set of conductive structures 514 is located on afifth level. In some embodiments, the fifth level of memory circuit 500is metal two (M2). In some embodiments, the M2 level is positioned aboveat least the active region, the M0 level, the POLY level, the MD levelor the M1 level of memory circuit 500.

In some embodiments, conductive structures 524 a, 524 c arecorresponding conductive structures 330 a, 330 c of FIG. 3. In someembodiments, conductive structure 514 e is source line SL1 of FIG. 3 orsource line SL1 of FIG. 1.

In some embodiments, conductive structure 524 a is electrically coupledto at least conductive structure 514 a by via 530 a.

In some embodiments, conductive structure 524 c is electrically coupledto at least conductive structure 514 c by via 530 c.

In some embodiments, conductive structure 524 e is electrically coupledto at least conductive structure 514 e by at least via 532 a or via 532d. In some embodiments, conductive structures 514 e, 524 e located ontwo different metal levels corresponds to source line SL1 of memorycircuit 300 or 500 or memory cell 100 of FIG. 1 resulting in lessresistance than other approaches.

In some embodiments, memory circuit 500 includes a source line SL1(e.g., either conductive structure 514 e or conductive structure 524 e)positioned on a single metal level.

Other quantities or configurations of the set of conductive structures524 are within the scope of the present disclosure.

Memory circuit 500 further includes one or more vias 538 a, 538 c(collectively referred to as a “set of vias 538”). In some embodiments,set of vias 538 electrically couple the set of conductive structures 524to upper metal layers (e.g., M3). In some embodiments, set of vias 538is in the V2 level of memory circuit 500. The V2 level of memory circuit500 is between the fifth level and a sixth level of memory circuit 500.Other quantities or configurations of the set of vias 538 are within thescope of the present disclosure.

Memory circuit 500 further includes one or more conductive structures534 a, 534 c (collectively referred to as a “set of conductivestructures 534”) and one or more conductive structures 536 a, 536 b(collectively referred to as a “set of conductive structures 536”)extending in at least the first direction X or the second direction Y.

The set of conductive structures 534 or 536 is located on a sixth level.In some embodiments, the sixth level of memory circuit 500 is metalthree (M3). In some embodiments, the M3 level is positioned above atleast the active region, the M0 level, the POLY level, the MD level, theM1 level or the M2 level of memory circuit 500.

The set of conductive structures 534 is set of conductive structures 330of memory circuit 300. In some embodiments, conductive structures 534 a,534 c are corresponding conductive structures 320 a, 320 c of FIG. 3.

Conductive structure 536 a is corresponding word line WL1 of memorycells 202[1,1] and 202[1,2] of FIG. 2 or memory cells 302[1,1] and302[1,2] of FIG. 3. Conductive structure 536 b is corresponding wordline WL2 of memory cells 202[2,1] and 202[2,2] of FIG. 2 or memory cells302[2,1] and 302[2,2] of FIG. 3. In some embodiments, at least word lineWL1 or word line WL2 is coupled to the corresponding gate 516 a, 516 bin a column (not shown) of memory circuit 500 that includes strap cells.In some embodiments, strap cells are memory cells configured to providevoltage pick-up and to provide N-well or P-well bias of the activeregion that prevents voltage drop along word lines WL that result in adifference in memory cell device voltages along the word lines WL as theword lines WL extend along memory cell array 200, memory circuit 300 or500. In some embodiments, memory cell array 200 is surrounded by twocolumns of strap cells.

In some embodiments, conductive structure 534 a is electrically coupledto at least conductive structure 524 a by via 538 a. In someembodiments, conductive structure 534 c is electrically coupled to atleast conductive structure 524 c by via 538 c.

Other quantities or configurations of the set of conductive structures534 or 536 are within the scope of the present disclosure.

Memory circuit 500 further includes one or more resistive switchingelements 550 a, 550 c (hereinafter referred to as a “set of resistiveswitching elements 550”.)

The set of resistive switching elements 550 are set of resistiveswitching elements 350 of FIG. 3. In some embodiments, resistiveswitching elements 550 a, 550 c are corresponding resistive switchingelements 350 a, 350 c of FIG. 3. At least one of the set of resistiveswitching elements 550 is resistive switching element 104 of FIG. 1.

The set of resistive switching elements 550 is located on a seventhlevel. In some embodiments, the seventh level of memory circuit 500 isabove the M3 level and below the M4 level. In some embodiments, theseventh level is positioned above at least the active region, the M0level, the POLY level, the MD level, the M1 level, the M2 level or theM3 level of memory circuit 500.

Resistive switching elements 550 a, 550 c include corresponding bottomelectrodes 552 a, 552 c (collectively referred to as a “set of bottomelectrodes 552”), corresponding resistive switching materials 554 a, 554c (collectively referred to as a “set of resistive switching material554”) and corresponding top electrodes 560 a, 560 c (collectivelyreferred to as a “set of top electrodes 560.”)

At least one of the bottom electrodes of the set of bottom electrodes552 corresponds to the bottom electrode 104 a of FIG. 1. Bottomelectrodes 552 a, 552 c are above corresponding conductive structures534 a, 534 c.

At least one of the resistive switching materials of the set ofresistive switching materials 554 corresponds to resistive switchingmaterial 104 b of FIG. 1. Resistive switching materials 554 a, 554 coverlap at least a portion of corresponding conductive structures 534 a,534 c. Resistive switching materials 554 a, 554 c overlap correspondingbottom electrodes 552 a, 552 c. Resistive switching materials 554 a, 554c are above corresponding bottom electrodes 552 a, 552 c.

At least one of the top electrodes of the set of top electrodes 560corresponds to top electrode 104 c of FIG. 1. Top electrodes 560 a, 560c are above corresponding resistive switching materials 554 a, 554 c andcorresponding bottom electrodes 552 a, 552 c.

Other configurations or quantities of elements in the set of resistiveswitching elements 550, set of bottom electrodes 552, set of resistiveswitching materials 554, set of top electrodes 560 are within the scopeof the present disclosure.

Memory circuit 500 further includes one or more conductive structures540 a, 540 b (hereinafter referred to as a “set of conductive structures540”) extending in the second direction Y.

The set of conductive structures 540 is located on an eighth level. Insome embodiments, the eighth level of memory circuit 500 is metal four(M4). In some embodiments, the M4 level is positioned above at least theactive region, the M0 level, the POLY level, the MD level, the M1 level,the M2 level or the M3 level of memory circuit 500.

Conductive structures 540 a, 540 b are corresponding bit lines BL1, BL2of memory circuit 500. At least one conductive structure of the set ofconductive structures 540 is bit line BL1 of FIG. 1. In someembodiments, conductive structure 540 a is at least conductive structure340 a or 340 b of FIG. 3. In some embodiments, conductive structure 540b is at least conductive structure 340 c or 340 d of FIG. 3. In someembodiments, conductive structures 540 a, 540 b are corresponding bitlines BL1, BL2 of FIG. 3.

Conductive structures 540 a, 540 b are above corresponding resistiveswitching elements 550 a, 550 c. Conductive structures 540 a, 540 boverlap corresponding resistive switching elements 550 a, 550 c. In someembodiments, set of conductive structures 540 is electrically coupled tothe set of resistive switching elements 550. In some embodiments,conductive structures 540 a, 540 b is electrically coupled tocorresponding top electrodes 560 a, 560 c. In some embodiments, set ofconductive structures 540 is electrically coupled to the set ofconductive structures 534 by the set of resistive switching elements550. In some embodiments, conductive structures 540 a, 540 b iselectrically coupled to corresponding conductive structures 534 a, 534 cby corresponding resistive switching elements 550 a, 550 c.

Other configurations or quantities of patterns in the set of conductivestructures 540 are within the scope of the present disclosure.

Memory circuit 500 further includes one or more vias 572 a, 572 b, 572e, 572 f (collectively referred to as a “set of vias 572”). In someembodiments, set of vias 572 electrically couple the set of conductivestructures 540 to upper metal layers (e.g., M5). In some embodiments,set of vias 572 is in the V4 level of memory circuit 500. The V4 levelof memory circuit 500 is between an eighth level and a ninth level ofmemory circuit 500. Other quantities or configurations of the set ofvias 572 are within the scope of the present disclosure.

Memory circuit 500 further includes one or more conductive structures570 a, 570 b (hereinafter referred to as a “set of conductive structures570”) extending in the second direction Y. The set of conductivestructures 570 is located on a ninth level. In some embodiments, theninth level of memory circuit 500 is metal five (M5). In someembodiments, the M5 level is positioned above at least the activeregion, the M0 level, the POLY level, the MD level, the M1 level, the M2level, the M3 level or the M4 level of memory circuit 500.

In some embodiments, conductive structures 570 a, 570 b arecorresponding bit lines BL1, BL2 of memory circuit 500. At least oneconductive structure of the set of conductive structures 570 is bit lineBL1 of FIG. 1. In some embodiments, conductive structures 570 a, 570 bare corresponding bit lines BL1, BL2 of FIG. 3.

In some embodiments, conductive structure 570 a is electrically coupledto at least conductive structure 540 a by at least via 572 a or 572 b.

In some embodiments, conductive structure 570 b is electrically coupledto at least conductive structure 540 b by at least via 572 e or 572 f.

In some embodiments, conductive structures 570 a, 540 a located on twodifferent metal levels corresponds to bit line BL1 of memory circuit 300or 500 or memory cell 100 of FIG. 1 resulting in less resistance thanother approaches. In some embodiments, conductive structures 570 b, 540b located on two different metal levels corresponds to bit line BL2 ofmemory circuit 300 or 500 or memory cell 100 of FIG. 1 resulting in lessresistance than other approaches.

In some embodiments, a width of one of conductive structure 514 e, 524e, 540 a, 540 b, 570 a or 570 b is the same as a width of another ofconductive structure 514 e, 524 e, 540 a, 540 b, 570 a or 570 b. In someembodiments, a width of one of conductive structure 514 e, 524 e, 540 a,540 b, 570 a or 570 b is different from a width of another of conductivestructure 514 e, 524 e, 540 a, 540 b, 570 a or 570 b.

In some embodiments, a width of one of conductive structure 514 e, 524 eis the same as a width of one of conductive structure 540 a, 540 b, 570a or 570 b resulting in less difference between the resistance of thebit lines BL1, BL2 and source lines SL1 compared with other approaches.

In some embodiments, memory circuit 500 includes a bit line BL1 (e.g.,either conductive structure 540 a or conductive structure 570 a)positioned on a single metal level. In some embodiments, memory circuit500 includes a bit line BL2 (e.g., either conductive structure 540 b orconductive structure 570 b) positioned on a single metal level.

Other configurations or quantities of patterns in the set of conductivestructures 570 are within the scope of the present disclosure.

Method

FIG. 6 is a flowchart of a method 600 of forming or manufacturing amemory circuit in accordance with some embodiments. It is understoodthat additional operations may be performed before, during, and/or afterthe method 600 depicted in FIG. 6, and that some other operations mayonly be briefly described herein. In some embodiments, the method 600 isusable to form memory circuits, such as memory cell 100 (FIG. 1), memorycell array 200 (FIG. 2), memory circuit 300 (FIG. 3) or memory circuit500 (FIGS. 5A-5E). In some embodiments, the method 600 is usable to formmemory circuits having similar structural relationships as one or moreof layout design 400 (FIGS. 4A-4H).

In operation 602 of method 600, a layout design 400 of a memory circuit(e.g., memory cell 100, memory cell array 200, memory circuit 300 or500) is generated. Operation 602 is performed by a processing device(e.g., processor 802 (FIG. 8)) configured to execute instructions forgenerating a layout design 400. In some embodiments, the layout design400 is a graphic database system (GDSII) file format.

In operation 604 of method 600, the memory circuit (e.g., memory cell100, memory cell array 200, memory circuit 300 or 500) is manufacturedbased on layout design 400. In some embodiments, operation 604 of method600 comprises manufacturing at least one mask based on the layout design400, and manufacturing the memory circuit (e.g., memory cell 100, memorycell array 200, memory circuit 300 or 500) based on the at least onemask.

FIG. 7 is a flowchart of a method 700 of generating a layout design of amemory circuit in accordance with some embodiments. It is understoodthat additional operations may be performed before, during, and/or afterthe method 700 depicted in FIG. 7, and that some other processes mayonly be briefly described herein. In some embodiments, the method 700 isusable to generate one or more layout patterns of layout design 400(FIGS. 4A-4H) of a memory circuit (e.g., memory cell 100, memory cellarray 200, memory circuit 300 or 500).

In operation 702 of method 700, a first set of memory cell layoutpatterns (e.g., memory cell layout pattern 402[1,1] or 402[2,1]) isgenerated or placed on layout design 400. In some embodiments, the firstset of memory cell layout patterns corresponds to fabricating a firstset of memory cells (e.g., memory cells 302[1,1] or 302[2,1] or memorycell 502 a) arranged in a first column (e.g., column 1) of memory cells.In some embodiments, each of the layout patterns of the first set ofmemory cell layout patterns is separated from an adjacent layout patternof the first set of memory cell layout patterns in second direction Y.

In some embodiments, operation 702 comprises at least operation 702 a(not shown) or operation 702 b (not shown).

In some embodiments, operation 702 a comprises generating or placing aset of selector element layout patterns (e.g., selector element layoutpattern 404 a, 404 b) on layout design 400. In some embodiments,selector element layout patterns 404 a, 404 b correspond to fabricatingselector elements 314 a, 314 b arranged in the first column (e.g.,column 1) of memory cells. In some embodiments, each of the layoutpatterns of the set of selector element layout patterns is separatedfrom an adjacent layout pattern of the set of selector element in thesecond direction Y and is located on a first set of layout levels (e.g.,layout levels OD-M1).

In some embodiments, operation 702 b comprises generating or placing aset of resistive switching element layout patterns (e.g., resistiveswitching element layout patterns 450 a, 450 b) on layout design 400. Insome embodiments, set of resistive switching element layout patterns(e.g., resistive switching element layout patterns 450 a, 450 b)corresponds to fabricating a set of resistive switching elements 350 or550 arranged in the first column (e.g., column 1) of memory cells. Insome embodiments, each of the layout patterns of the set of resistiveswitching element layout patterns is separated from an adjacent layoutpattern of the set of resistive switching element layout patterns in thesecond direction Y, and is located on a second set of layout levels(e.g., layout levels M3-M4) above the first set of layout levels.

In operation 704 of method 700, a second set of memory cell layoutpatterns (e.g., memory cell layout pattern 402[1,2] or 402[2,2]) isgenerated or placed on layout design 400. In some embodiments, thesecond set of memory cell layout patterns corresponds to fabricating asecond set of memory cells (e.g., memory cells 302[1,2] or 302[2,2] ormemory cell 502 b) arranged in a second column (e.g., column 2) ofmemory cells. In some embodiments, each of the layout patterns of thesecond set of memory cell layout patterns is separated from an adjacentlayout pattern of the second set of memory cell layout patterns insecond direction Y.

In some embodiments, operation 704 comprises at least operation 704 a(not shown) or operation 704 b (not shown).

In some embodiments, operation 704 a comprises generating or placing aset of selector element layout patterns (e.g., selector element layoutpattern 404 c, 404 d) on layout design 400. In some embodiments,selector element layout patterns 404 c, 404 d correspond to fabricatingselector elements 314 c, 314 d arranged in the second column (e.g.,column 2) of memory cells. In some embodiments, each of the layoutpatterns of the set of selector element layout patterns is separatedfrom an adjacent layout pattern of the set of selector element in thesecond direction Y and is located on the first set of layout levels(e.g., layout levels OD-M1).

In some embodiments, operation 704 b comprises generating or placing aset of resistive switching element layout patterns (e.g., resistiveswitching element layout patterns 450 c, 450 d) on layout design 400. Insome embodiments, set of resistive switching element layout patterns(e.g., resistive switching element layout patterns 450 c, 450 d)corresponds to fabricating a set of resistive switching elements 350 or550 arranged in the second column (e.g., column 2) of memory cells. Insome embodiments, each of the layout patterns of the set of resistiveswitching element layout patterns is separated from an adjacent layoutpattern of the set of resistive switching element layout patterns in thesecond direction Y, and is located on the second set of layout levels(e.g., layout levels M3-M4).

In some embodiments, at least operation 702 b or 704 b comprises atleast operation 705 a (not shown), operation 705 b (not shown) oroperation 705 c (not shown).

In some embodiments, operation 705 a comprises generating or placing abottom electrode layout pattern 452 a, 452 b, 452 c or 452 d on layoutlevel BE. In some embodiments, bottom electrode layout pattern 452 a,452 b, 452 c or 452 d corresponds to fabricating bottom electrode 104 a,552 a or 552 c.

In some embodiments, operation 705 b comprises generating or placing aresistive switching material layout pattern 454 a, 454 b, 454 c or 454 don layout level TMO. In some embodiments, resistive switching materiallayout pattern 454 a, 454 b, 454 c or 454 d corresponds to fabricatingresistive switching material 104 b, 554 a or 554 c.

In some embodiments, operation 705 c comprises generating or placing atop electrode layout pattern 460 a, 460 b, 460 c or 460 d on layoutlevel TE. In some embodiments, top electrode layout pattern 460 a, 460b, 460 c or 460 d corresponds to fabricating top electrode 104 c, 560 aor 560 c.

In some embodiments, operation 706 comprises generating or placing asource line layout pattern (e.g., at least conductive feature layoutpattern 414 e or 424 e) on layout design 400.

In some embodiments, operation 706 comprises at least operation 706 a(not shown).

In some embodiments, operation 706 a comprises generating or placing afirst set of conductive feature layout patterns (e.g., conductivefeature layout pattern 414 e) extending in the second direction Y. Insome embodiments, conductive feature layout pattern 414 e is positionedbetween the first set of memory cell layout patterns and the second setof memory cell layout patterns. In some embodiments, the first set ofconductive feature layout patterns (e.g., conductive feature layoutpattern 414 e) corresponds to fabricating a source line SL1 in FIGS. 1-3and 5 that extends in the second direction Y and is coupled to the firstset of memory cells and the second set of memory cells. In someembodiments, the first set of conductive feature layout patterns (e.g.,conductive feature layout pattern 414 e) is located on the M1 layoutlevel.

In some embodiments, operation 706 further comprises at least operation706 b (not shown) or operation 706 c (not shown).

In some embodiments, operation 706 b comprises generating or placing asecond set of conductive feature layout patterns (e.g., conductivefeature layout pattern 424 e) extending in the second direction Y. Insome embodiments, conductive feature layout pattern 424 e is positionedbetween the first set of memory cell layout patterns and the second setof memory cell layout patterns. In some embodiments, the second set ofconductive feature layout patterns (e.g., conductive feature layoutpattern 424 e) corresponds to fabricating source line SL1 in FIGS. 1-3and 5 that extends in the second direction Y and is coupled to the firstset of memory cells and the second set of memory cells. In someembodiments, the second set of conductive feature layout patterns (e.g.,conductive feature layout pattern 424 e) is located on the M2 layoutlevel different from the M1 layout level.

In some embodiments, operation 706 c comprises generating or placing aset of via layout patterns (e.g., set of via layout patterns 432) onlayout design 400. In some embodiments, the set of via layout patternsis located between the M1 layout level and the M2 layout level. In someembodiments, the set of via layout patterns (e.g., set of via layoutpatterns 432) corresponds to fabricating a set of vias 532 coupledbetween the source line SL1 and another portion of the source line SL1.In some embodiments, set of vias 532 are coupled between conductivefeature layout pattern 424 e and conductive feature layout pattern 414e.

In some embodiments, operation 708 comprises generating or placing afirst bit line layout pattern (e.g., at least conductive feature layoutpattern 440 a) on layout design 400.

In some embodiments, operation 708 comprises at least operation 708 a(not shown).

In some embodiments, operation 708 a comprises generating or placing athird set of conductive feature layout patterns (e.g., conductivefeature layout pattern 440 a) extending in the second direction Y. Insome embodiments, the third set of conductive feature layout patterns(e.g., conductive feature layout pattern 440 a) is located on a M4layout level. In some embodiments, the third set of conductive featurelayout patterns (e.g., conductive feature layout pattern 440 a)corresponds to fabricating a first portion (e.g., 540 a) of a first bitline BL1 coupled to the first set of memory cells.

In some embodiments, operation 708 further comprises at least operation708 b or 708 c.

In some embodiments, operation 708 a comprises generating or placing afourth set of conductive feature layout patterns (e.g., conductivefeature layout pattern 470 a) extending in the second direction Y. Insome embodiments, the fourth set of conductive feature layout patterns(e.g., conductive feature layout pattern 470 a) is located on a M5layout level. In some embodiments, the fourth set of conductive featurelayout patterns (e.g., conductive feature layout pattern 470 a)corresponds to fabricating a second portion (e.g., 570 a) of the firstbit line BL1 coupled to the first set of memory cells.

In some embodiments, operation 708 b comprises generating or placing aset of via layout patterns (e.g., via layout patterns 472 a, 427 b, 472c, 472 d) between the third set of conductive feature layout patterns(e.g., conductive feature layout pattern 470 a) and the fourth set ofconductive feature layout patterns (e.g., conductive feature layoutpattern 440 a). In some embodiments, the set of via layout patterns(e.g., via layout patterns 472 a, 427 b, 472 c, 472 d) corresponds tofabricating vias 572 a, 572 b coupled between the first portion of thefirst bit line BL1 and the second portion of the first bit line BL1.

In some embodiments, operation 710 comprises generating or placing asecond bit line layout pattern (e.g., at least conductive feature layoutpattern 440 b) on layout design 400.

In some embodiments, operation 710 comprises at least operation 710 a(not shown).

In some embodiments, operation 710 a comprises generating or placing afifth set of conductive feature layout patterns (e.g., conductivefeature layout pattern 440 b) extending in the second direction Y. Insome embodiments, the fifth set of conductive feature layout patterns(e.g., conductive feature layout pattern 440 b) is located on the M4layout level. In some embodiments, the fifth set of conductive featurelayout patterns (e.g., conductive feature layout pattern 440 b)corresponds to fabricating a first portion (e.g., 540 b) of a second bitline BL2 coupled to the second set of memory cells.

In some embodiments, operation 710 further comprises at least operation710 b or 710 c.

In some embodiments, operation 710 a comprises generating or placing asixth set of conductive feature layout patterns (e.g., conductivefeature layout pattern 470 b) extending in the second direction Y. Insome embodiments, the sixth set of conductive feature layout patterns(e.g., conductive feature layout pattern 470 b) is located on the M5layout level. In some embodiments, the sixth set of conductive featurelayout patterns (e.g., conductive feature layout pattern 470 b)corresponds to fabricating a second portion (e.g., 570 b) of the secondbit line BL2 coupled to the second set of memory cells.

In some embodiments, operation 710 b comprises generating or placing aset of via layout patterns (e.g., via layout patterns 472 e, 427 f, 472g, 472 h) between the sixth set of conductive feature layout patterns(e.g., conductive feature layout pattern 470 b) and the fifth set ofconductive feature layout patterns (e.g., conductive feature layoutpattern 440 b). In some embodiments, the set of via layout patterns(e.g., via layout patterns 472 e, 427 f, 472 g, 472 h) corresponds tofabricating vias 572 e, 572 f coupled between the first portion of thesecond bit line BL2 and the second portion of the second bit line BL2.

In some embodiments, layout design 400 is a standard cell. In someembodiments, one or more of operations 702, 704, 706, 708 or 710 is notperformed.

One or more of the operations of methods 600-700 is performed by aprocessing device configured to execute instructions for manufacturing amemory circuit, such as memory cell 100, memory circuit 300 or 500, or amemory array, such as memory cell array 200. In some embodiments, one ormore operations of methods 600-700 is performed using a same processingdevice as that used in a different one or more operations of methods600-700. In some embodiments, a different processing device is used toperform one or more operations of methods 600-700 from that used toperform a different one or more operations of methods 600-700.

FIG. 8 is a schematic view of a system 800 for designing an IC layoutdesign in accordance with some embodiments. In some embodiments, system800 generates or places one or more IC layout designs described herein.System 800 includes a hardware processor 802 and a non-transitory,computer readable storage medium 804 encoded with, i.e., storing, thecomputer program code 806, i.e., a set of executable instructions.Computer readable storage medium 804 is configured for interfacing withmanufacturing machines for producing the integrated circuit. Theprocessor 802 is electrically coupled to the computer readable storagemedium 804 via a bus 808. The processor 802 is also electrically coupledto an I/O interface 810 by bus 808. A network interface 812 is alsoelectrically connected to the processor 802 via bus 808. Networkinterface 812 is connected to a network 814, so that processor 802 andcomputer readable storage medium 804 are capable of connecting toexternal elements via network 814. The processor 802 is configured toexecute the computer program code 806 encoded in the computer readablestorage medium 804 in order to cause system 800 to be usable forperforming a portion or all of the operations as described in method 600or 700.

In some embodiments, the processor 802 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 804 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 804 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments using optical disks, the computerreadable storage medium 804 includes a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the computer readable storage medium 804 stores thecomputer program code 806 configured to cause system 800 to performmethod 600 or 700. In some embodiments, the computer readable storagemedium 804 also stores information needed for performing method 600 or700 as well as information generated during performing method 600 or700, such as layout design 816, user interface 818, fabrication unit820, and/or a set of executable instructions to perform the operation ofmethod 600 or 700. In some embodiments, layout design 816 comprises oneor more of layout patterns of layout design 400.

In some embodiments, the computer readable storage medium 804 storesinstructions (e.g., computer program code 806) for interfacing withmanufacturing machines. The instructions (e.g., computer program code806) enable processor 802 to generate manufacturing instructionsreadable by the manufacturing machines to effectively implement method600 or 700 during a manufacturing process.

System 800 includes I/O interface 810. I/O interface 810 is coupled toexternal circuitry. In some embodiments, I/O interface 810 includes akeyboard, keypad, mouse, trackball, trackpad, and/or cursor directionkeys for communicating information and commands to processor 802.

System 800 also includes network interface 812 coupled to the processor802. Network interface 812 allows system 800 to communicate with network814, to which one or more other computer systems are connected. Networkinterface 812 includes wireless network interfaces such as BLUETOOTH,WIFI, WIMAX, GPRS, or WCDMA; or wired network interface such asETHERNET, USB, or IEEE-1394. In some embodiments, method 600 or 700 isimplemented in two or more systems 800, and information such as layoutdesign, and user interface are exchanged between different systems 800by network 814.

System 800 is configured to receive information related to a layoutdesign through I/O interface 810 or network interface 812. Theinformation is transferred to processor 802 by bus 808 to determine alayout design for producing IC or layout design 400. The layout designis then stored in computer readable storage medium 804 as layout design816. System 800 is configured to receive information related to a userinterface through I/O interface 810 or network interface 812. Theinformation is stored in computer readable storage medium 804 as userinterface 818.

In some embodiments, method 600 or 700 is implemented as a standalonesoftware application for execution by a processor. In some embodiments,method 600 or 700 is implemented as a software application that is apart of an additional software application. In some embodiments, method600 or 700 is implemented as a plug-in to a software application. Insome embodiments, method 600 or 700 is implemented as a softwareapplication that is a portion of an EDA tool. In some embodiments,method 600 or 700 is implemented as a software application that is usedby an EDA tool. In some embodiments, the EDA tool is used to generate alayout of the integrated circuit device. In some embodiments, the layoutis stored on a non-transitory computer readable medium. In someembodiments, the layout is generated using a tool such as VIRTUOSO®available from CADENCE DESIGN SYSTEMS, Inc., or another suitable layoutgenerating tool. In some embodiments, the layout is generated based on anetlist which is created based on the schematic design. In someembodiments, method 600 or 700 is implemented by a manufacturing deviceto manufacture an integrated circuit using a set of masks manufacturedbased on one or more layout designs generated by system 800. In someembodiments, system 800 is a manufacturing device to manufacture anintegrated circuit using a set of masks manufactured based on one ormore layout designs of the present disclosure. In some embodiments,system 800 of FIG. 8 generates layout designs of an integrated circuitthat are smaller than other approaches. In some embodiments, system 800of FIG. 8 generates layout designs of integrated circuit structure thatoccupy less area and provide better routing resources than otherapproaches.

FIG. 9 is a block diagram of an integrated circuit (IC) manufacturingsystem 900, and an IC manufacturing flow associated therewith, inaccordance with at least one embodiment of the present disclosure.

In FIG. 9, IC manufacturing system 900 includes entities, such as adesign house 920, a mask house 930, and an IC manufacturer/fabricator(“fab”) 940, that interact with one another in the design, development,and manufacturing cycles and/or services related to manufacturing an ICdevice 960. The entities in system 900 are connected by a communicationsnetwork. In some embodiments, the communications network is a singlenetwork. In some embodiments, the communications network is a variety ofdifferent networks, such as an intranet and the Internet. Thecommunications network includes wired and/or wireless communicationchannels. Each entity interacts with one or more of the other entitiesand provides services to and/or receives services from one or more ofthe other entities. In some embodiments, two or more of design house920, mask house 930, and IC fab 940 is owned by a single larger company.In some embodiments, two or more of design house 920, mask house 930,and IC fab 940 coexist in a common facility and use common resources.

Design house (or design team) 920 generates an IC design layout 922. ICdesign layout 922 includes various geometrical patterns designed for anIC device 960. The geometrical patterns correspond to patterns of metal,oxide, or semiconductor layers that make up the various components of ICdevice 960 to be fabricated. The various layers combine to form variousIC features. For example, a portion of IC design layout 922 includesvarious IC features, such as an active region, gate electrode, sourceelectrode and drain electrode, metal lines or vias of an interlayerinterconnection, and openings for bonding pads, to be formed in asemiconductor substrate (such as a silicon wafer) and various materiallayers disposed on the semiconductor substrate. Design house 920implements a proper design procedure to form IC design layout 922. Thedesign procedure includes one or more of logic design, physical designor place and route. IC design layout 922 is presented in one or moredata files having information of the geometrical patterns. For example,IC design layout 922 can be expressed in a GDSII file format or DFIIfile format.

Mask house 930 includes data preparation 932 and mask fabrication 934.Mask house 930 uses IC design layout 922 to manufacture one or moremasks to be used for fabricating the various layers of IC device 960according to IC design layout 922. Mask house 930 performs mask datapreparation 932, where IC design layout 922 is translated into arepresentative data file (“RDF”). Mask data preparation 932 provides theRDF to mask fabrication 934. Mask fabrication 934 includes a maskwriter. A mask writer converts the RDF to an image on a substrate, suchas a mask (reticle) or a semiconductor wafer. The design layout ismanipulated by mask data preparation 932 to comply with particularcharacteristics of the mask writer and/or requirements of IC fab 940. InFIG. 9, mask data preparation 932 and mask fabrication 934 areillustrated as separate elements. In some embodiments, mask datapreparation 932 and mask fabrication 934 can be collectively referred toas mask data preparation.

In some embodiments, mask data preparation 932 includes opticalproximity correction (OPC) which uses lithography enhancement techniquesto compensate for image errors, such as those that can arise fromdiffraction, interference, other process effects and the like. OPCadjusts IC design layout 922. In some embodiments, mask data preparation932 includes further resolution enhancement techniques (RET), such asoff-axis illumination, sub-resolution assist features, phase-shiftingmasks, other suitable techniques, and the like or combinations thereof.In some embodiments, inverse lithography technology (ILT) is also used,which treats OPC as an inverse imaging problem.

In some embodiments, mask data preparation 932 includes a mask rulechecker (MRC) that checks the IC design layout that has undergoneprocesses in OPC with a set of mask creation rules which contain certaingeometric and/or connectivity restrictions to ensure sufficient margins,to account for variability in semiconductor manufacturing processes, andthe like. In some embodiments, the MRC modifies the IC design layout tocompensate for limitations during mask fabrication 934, which may undopart of the modifications performed by OPC in order to meet maskcreation rules.

In some embodiments, mask data preparation 932 includes lithographyprocess checking (LPC) that simulates processing that will beimplemented by IC fab 940 to fabricate IC device 960. LPC simulates thisprocessing based on IC design layout 922 to create a simulatedmanufactured device, such as IC device 960. The processing parameters inLPC simulation can include parameters associated with various processesof the IC manufacturing cycle, parameters associated with tools used formanufacturing the IC, and/or other aspects of the manufacturing process.LPC takes into account various factors, such as aerial image contrast,depth of focus (“DOF”), mask error enhancement factor (“MEEF”), othersuitable factors, and the like or combinations thereof. In someembodiments, after a simulated manufactured device has been created byLPC, if the simulated device is not close enough in shape to satisfydesign rules, OPC and/or MRC are be repeated to further refine IC designlayout 922.

It should be understood that the above description of mask datapreparation 932 has been simplified for the purposes of clarity. In someembodiments, data preparation 932 includes additional features such as alogic operation (LOP) to modify the IC design layout according tomanufacturing rules. Additionally, the processes applied to IC designlayout 922 during data preparation 932 may be executed in a variety ofdifferent orders.

After mask data preparation 932 and during mask fabrication 934, a maskor a group of masks are fabricated based on the modified IC designlayout. In some embodiments, an electron-beam (e-beam) or a mechanism ofmultiple e-beams is used to form a pattern on a mask (photomask orreticle) based on the modified IC design layout. The mask can be formedin various technologies. In some embodiments, the mask is formed usingbinary technology. In some embodiments, a mask pattern includes opaqueregions and transparent regions. A radiation beam, such as anultraviolet (UV) beam, used to expose the image sensitive material layer(e.g., photoresist) which has been coated on a wafer, is blocked by theopaque region and transmits through the transparent regions. In oneexample, a binary mask includes a transparent substrate (e.g., fusedquartz) and an opaque material (e.g., chromium) coated in the opaqueregions of the mask. In another example, the mask is formed using aphase shift technology. In the phase shift mask (PSM), various featuresin the pattern formed on the mask are configured to have proper phasedifference to enhance the resolution and imaging quality. In variousexamples, the phase shift mask can be attenuated PSM or alternating PSM.The mask(s) generated by mask fabrication 934 is used in a variety ofprocesses. For example, such a mask(s) is used in an ion implantationprocess to form various doped regions in the semiconductor wafer, in anetching process to form various etching regions in the semiconductorwafer, and/or in other suitable processes.

IC fab 940 is an IC fabrication business that includes one or moremanufacturing facilities for the fabrication of a variety of differentIC products. In some embodiments, IC Fab 940 is a semiconductor foundry.For example, there may be a manufacturing facility for the front endfabrication of a plurality of IC products (front-end-of-line (FEOL)fabrication), while a second manufacturing facility may provide the backend fabrication for the interconnection and packaging of the IC products(back-end-of-line (BEOL) fabrication), and a third manufacturingfacility may provide other services for the foundry business.

IC fab 940 uses the mask (or masks) fabricated by mask house 930 tofabricate IC device 960. Thus, IC fab 940 at least indirectly uses ICdesign layout 922 to fabricate IC device 960. In some embodiments, asemiconductor wafer 942 is fabricated by IC fab 940 using the mask (ormasks) to form IC device 960. Semiconductor wafer 942 includes a siliconsubstrate or other proper substrate having material layers formedthereon. Semiconductor wafer further includes one or more of variousdoped regions, dielectric features, multilevel interconnects, and thelike (formed at subsequent manufacturing steps).

Details regarding an integrated circuit (IC) manufacturing system (e.g.,system 900 of FIG. 9), and an IC manufacturing flow associated therewithare found, e.g., in U.S. Pat. No. 9,256,709, granted Feb. 9, 2016, U.S.Pre-Grant Publication No. 20150278429, published Oct. 1, 2015, U.S.Pre-Grant Publication No. 20140040838, published Feb. 6, 2014, and U.S.Pat. No. 7,260,442, granted Aug. 21, 2007, the entireties of each ofwhich are hereby incorporated by reference.

It will be readily seen by one of ordinary skill in the art that one ormore of the disclosed embodiments fulfill one or more of the advantagesset forth above. After reading the foregoing specification, one ofordinary skill will be able to affect various changes, substitutions ofequivalents and various other embodiments as broadly disclosed herein.It is therefore intended that the protection granted hereon be limitedonly by the definition contained in the appended claims and equivalentsthereof.

One aspect of this description relates to a memory cell array. Thememory cell array includes a first column of memory cells, a secondcolumn of memory cells, a first bit line, a second bit line and a sourceline. The second column of memory cells is separated from the firstcolumn of memory cells in a first direction. The first column of memorycells and the second column of memory cells are arranged in a seconddirection different from the first direction. The first bit line iscoupled to the first column of memory cells and extends in the seconddirection. The second bit line is coupled to the second column of memorycells and extends in the second direction. The source line extends inthe second direction, is coupled to the first column of memory cells andthe second column of memory cells. In some embodiments, each memory cellof the first column of memory cells or the second column of memory cellsis a non-volatile memory cell. In some embodiments, the non-volatilememory cell includes one or more of a resistance random access memory(RRAM), a ferroelectric RAM (FRAM) or a Magnetoresistive RAM (MRAM). Insome embodiments, a resistance of the first bit line or a resistance ofthe second bit line is substantially equal to a resistance of the sourceline. In some embodiments, the source line includes a first conductiveline extending in the second direction, and being located on a firstmetal layer. In some embodiments, the source line further includes asecond conductive line and a set of vias. The second conductive lineextends in the second direction, and is located on a second metal layerabove the first metal layer. The set of vias is electrically coupled tothe first conductive line and the second conductive line, and is locatedbetween the first conductive line and the second conductive line. Insome embodiments, the first metal layer is a metal 1 (M1) layer, and thesecond metal layer is a metal 2 (M2) layer. In some embodiments, thefirst bit line or the second bit line includes a first conductive lineextending in the second direction, and being located on a first metallayer. In some embodiments, the first bit line or the second bit linefurther includes a second conductive line and a set of vias. The secondconductive line extends in the second direction, and is located on asecond metal layer above the first metal layer. The set of vias iselectrically coupled to the first conductive line and the secondconductive line, and is located between the first conductive line andthe second conductive line. In some embodiments, the first metal layeris a metal 4 (M4) layer, and the second metal layer is a metal 5 (M5)layer.

Another aspect of this description relates to a memory cell array. Thememory cell array includes a first set of memory cells, a second set ofmemory cells, a first bit line, a second bit line and a source line. Thefirst set of memory cells is arranged in a first column and a firstdirection. The second set of memory cells is arranged in a second columnand the first direction, and is separated from the first set of memorycells in a second direction different from the first direction. Thefirst bit line is coupled to the first set of memory cells and extendsin the first direction. The second bit line is coupled to the second setof memory cells and extends in the first direction. The source lineextends in the first direction, is coupled to the first set of memorycells and the second set of memory cells, and is positioned between thefirst set of memory cells and the second set of memory cells. The sourceline includes a first portion and a second portion. The first portionextends in the first direction and is located on a first metal layer.The second portion extends in the first direction and is located on asecond metal layer above the first metal layer. In some embodiments, thememory cell array further includes a word line extending in the seconddirection, and being coupled to a memory cell of the first set of memorycells in the first column and a memory cell of the second set of memorycells in the second column. In some embodiments, a width of the firstbit line or a width of the second bit line is substantially equal to awidth of the source line. In some embodiments, each memory cell of thefirst set of memory cells or the second set of memory cells includes aresistance switching element coupled to the first bit line or the secondbit line, and a switch coupled between the resistance switching elementand the source line.

Still another aspect of this description relates to a method of readingdata stored in a first memory cell. The method includes generating, by aprocessor, a layout design of the memory cell array and manufacturingthe memory cell array based on the layout design. In some embodiments,the generating of the layout design of the memory cell array includesgenerating a first set of memory cell layout patterns that correspondsto fabricating a first set of memory cells arranged in a first column ofmemory cells. In some embodiments, each of the layout patterns of thefirst set of memory cell layout patterns is separated from an adjacentlayout pattern of the first set of memory cell layout patterns in afirst direction. In some embodiments, the generating of the layoutdesign of the memory cell array further includes generating a second setof memory cell layout patterns that corresponds to fabricating a secondset of memory cells arranged in a second column of memory cells. In someembodiments, the second set of memory cell layout patterns is separatedfrom the first set of memory cell layout patterns in a second directiondifferent from the first direction. In some embodiments, each of thelayout patterns of the second set of memory cell layout patterns isseparated from an adjacent layout pattern of the second set of memorycell layout patterns in the first direction. In some embodiments, thegenerating of the layout design of the memory cell array furtherincludes generating a first set of conductive feature layout patternsextending in the first direction. In some embodiments, a layout patternof the first set of conductive feature layout patterns is positionedbetween the first set of memory cell layout patterns and the second setof memory cell layout patterns. In some embodiments, the first set ofconductive feature layout patterns corresponds to fabricating a sourceline extending in the first direction and being coupled to the first setof memory cells and the second set of memory cells. In some embodiments,the generating the layout design of the memory cell array furtherincludes generating a second set of conductive feature layout patternsextending in the first direction. In some embodiments, the second set ofconductive feature layout patterns is located on a first layout level.In some embodiments, the second set of conductive feature layoutpatterns corresponds to fabricating a first portion of a first bit linecoupled to the first set of memory cells. In some embodiments, thegenerating the layout design of the memory cell array further includesgenerating a third set of conductive feature layout patterns extendingin the first direction. In some embodiments, the third set of conductivefeature layout patterns is located on the first layout level. In someembodiments, the third set of conductive feature layout patterns isseparated from the second set of conductive feature layout patterns inthe second direction. In some embodiments, the third set of conductivefeature layout patterns corresponds to fabricating a first portion of asecond bit line coupled to the second set of memory cells. In someembodiments, the generating the layout design of the memory cell arrayfurther includes generating a fourth set of conductive feature layoutpatterns extending in the first direction. In some embodiments, thefourth set of conductive feature layout patterns is located on a secondlayout level different from the first layout level. In some embodiments,the fourth set of conductive feature layout patterns corresponds tofabricating a second portion of the first bit line. In some embodiments,the generating the layout design of the memory cell array furtherincludes generating a fifth set of conductive feature layout patternsextending in the first direction. In some embodiments, the fifth set ofconductive feature layout patterns is located on the second layoutlevel. In some embodiments, the fifth set of conductive feature layoutpatterns is separated from the fourth set of conductive feature layoutpatterns in the second direction. In some embodiments, the fifth set ofconductive feature layout patterns corresponds to fabricating a secondportion of the second bit line. In some embodiments, the generating thelayout design of the memory cell array further includes generating afirst set of via layout patterns. In some embodiments, the first set ofvia layout patterns is located between the second layout level and thefirst layout level. In some embodiments, the first set of via layoutpatterns corresponds to fabricating vias coupled between the firstportion of the first bit line and the second portion of the first bitline. In some embodiments, the generating the layout design of thememory cell array further includes generating a second set of via layoutpatterns. In some embodiments, the second set of via layout patterns islocated between the second layout level and the first layout level. Insome embodiments, the second set of via layout patterns corresponds tofabricating vias coupled between the first portion of the second bitline and the second portion of the second bit line. In some embodiments,the generating the layout design of the memory cell array furtherincludes generating a second set of conductive feature layout patternsextending in the first direction. In some embodiments, the second set ofconductive feature layout patterns is located on a second layout leveldifferent from the first layout level. In some embodiments, the secondset of conductive feature layout patterns corresponds to fabricatinganother portion of the source line. In some embodiments, the generatingthe layout design of the memory cell array further includes generating aset of via layout patterns. In some embodiments, the set of via layoutpatterns is located between the second layout level and the first layoutlevel. In some embodiments, the set of via layout patterns correspondsto fabricating vias coupled between the source line and another portionof the source line. In some embodiments, the generating the first set ofmemory cell layout patterns or the second set of memory cell layoutpatterns includes generating a set of selector element layout patternsthat corresponds to fabricating a set of selector elements arranged inthe first column or the second column of memory cells. In someembodiments, each of the layout patterns of the set of selector elementlayout patterns is separated from an adjacent layout pattern of the setof selector element in the first direction and is located on a first setof layout levels. In some embodiments, the generating the first set ofmemory cell layout patterns or the second set of memory cell layoutpatterns further includes generating a set of resistive switchingelement layout patterns that corresponds to fabricating a set ofresistive switching elements arranged in the first column or the secondcolumn of memory cells. In some embodiments, each of the layout patternsof the set of resistive switching element layout patterns is separatedfrom an adjacent layout pattern of the set of resistive switchingelement layout patterns in the first direction, and is located on asecond set of layout levels above the first set of layout levels. Insome embodiments, the generating the set of resistive switching elementlayout patterns includes generating a bottom electrode element layoutpattern that corresponds to fabricating a bottom electrode element. Insome embodiments, the bottom electrode element layout pattern is locatedon a first layout level. In some embodiments the generating the set ofresistive switching element layout patterns further includes generatinga resistive switching material layout pattern that corresponds tofabricating a resistive switching material. In some embodiments, theresistive switching material layout pattern is located on a secondlayout level different from the first layout level. In some embodimentsthe generating the set of resistive switching element layout patternsfurther includes generating a top electrode element layout pattern thatcorresponds to fabricating a top electrode element. In some embodiments,the top electrode element layout pattern is located on a third layoutlevel different from the first layout level and the second layout level.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A memory cell array comprising: a first column ofmemory cells; a second column of memory cells being separated from thefirst column of memory cells in a first direction, the first column ofmemory cells and the second column of memory cells being arranged in asecond direction different from the first direction; a first bit linecoupled to the first column of memory cells, and extending in the seconddirection; a second bit line coupled to the second column of memorycells, and extending in the second direction, the first bit line or thesecond bit line comprises: a first conductive line extending in thesecond direction, and being located on a first metal layer; and a secondconductive line extending in the second direction, and being located ona second metal layer above the first metal layer, the first conductiveline and the second conductive line overlap a source of a transistor ofa memory cell of the first set of memory cells; a source line extendingin the second direction, being coupled to the first column of memorycells and the second column of memory cells; and a first set of viaselectrically coupled to the first conductive line and the secondconductive line, and being between the first conductive line and thesecond conductive line, a pair of vias of the first set of vias beinglocated above where the first conductive line overlaps each memory cellof the first column of memory cells or the second column of memorycells.
 2. The memory cell array of claim 1, wherein each memory cell ofthe first column of memory cells or the second column of memory cells isa non-volatile memory cell.
 3. The memory cell array of claim 2, whereinthe non-volatile memory cell includes one or more of a resistance randomaccess memory (RRAM), a ferroelectric RAM (FRAM) or a MagnetoresistiveRAM (MRAM).
 4. The memory cell array of claim 1, wherein a resistance ofthe first bit line or a resistance of the second bit line issubstantially equal to a resistance of the source line.
 5. The memorycell array of claim 1, wherein the source line comprises: a thirdconductive line extending in the second direction, and being located ona third metal layer below the first metal layer.
 6. The memory cellarray of claim 5, wherein the source line further comprises: a fourthconductive line extending in the second direction, and being located ona fourth metal layer above the third metal layer and below the firstmetal layer; and a second set of vias electrically coupled to the thirdconductive line and the fourth conductive line, and being locatedbetween the third conductive line and the fourth conductive line.
 7. Thememory cell array of claim 6, wherein the third metal layer is a metal 1(M1) layer, and the fourth metal layer is a metal 2 (M2) layer.
 8. Thememory cell array of claim 1, wherein the first metal layer is a metal 4(M4) layer, and the second metal layer is a metal 5 (M5) layer.
 9. Thememory cell array of claim 1, wherein a length of the first conductiveline is substantially equal to a length of the second conductive line.10. A memory cell array comprising: a first set of memory cells arrangedin a first column and a first direction; a second set of memory cellsarranged in a second column and the first direction, and being separatedfrom the first set of memory cells in a second direction different fromthe first direction; a first bit line coupled to the first set of memorycells, and extending in the first direction, the first bit linecomprises: a first portion extending in the first direction, and beinglocated on a first metal layer; and a second portion extending in thefirst direction, and being located on a second metal layer above thefirst metal layer, the first portion and the second portion overlap asource of a transistor of a memory cell of the first set of memorycells; a second bit line coupled to the second set of memory cells, andextending in the first direction; and a source line extending in thefirst direction, being coupled to the first set of memory cells and thesecond set of memory cells, and being positioned between the first setof memory cells and the second set of memory cells, the source linecomprising: a third portion extending in the first direction, and beinglocated on a third metal layer below the first metal layer; and a fourthportion extending in the first direction, and being located on a fourthmetal layer below the third metal layer, the third portion and thefourth portion overlap drains of corresponding transistors ofcorresponding memory cells of the first set of memory cells; and a firstset of vias between the third portion and the fourth portion, and eachvia of the first set of vias being positioned above where the fourthportion overlaps each drain of the corresponding transistors of thecorresponding memory cells of the first set of memory cells.
 11. Thememory cell array of claim 10, further comprising a word line extendingin the second direction, and being coupled to the memory cell of thefirst set of memory cells in the first column and a memory cell of thesecond set of memory cells in the second column.
 12. The memory cellarray of claim 10, wherein a width of the first bit line or a width ofthe second bit line is substantially equal to a width of the sourceline.
 13. The memory cell array of claim 10, wherein each memory cell ofthe first set of memory cells or the second set of memory cellscomprises: a resistance switching element coupled to the first bit lineor the second bit line; and a switch coupled between the resistanceswitching element and the source line.
 14. The memory cell array ofclaim 10, wherein the third portion and the fourth portion furtheroverlap drains of corresponding transistors of corresponding memorycells of the second set of memory cells; and the source line furthercomprises: a second set of vias between the third portion and the fourthportion, and each via of the second set of vias being positioned abovewhere the fourth portion overlaps each drain of the correspondingtransistors of the corresponding memory cells of the second set ofmemory cells, the second set of vias being separated from the first setof vias in the second direction.
 15. A memory cell array comprising: afirst column of resistance random access memory (RRAM) cells; a secondcolumn of RRAM cells being separated from the first column of RRAM cellsin a first direction, the first column of RRAM cells and the secondcolumn of RRAM cells being arranged in a second direction different fromthe first direction; a first bit line coupled to the first column ofRRAM cells, and extending in the second direction; a second bit linecoupled to the second column of RRAM cells, and extending in the seconddirection; a word line extending in the first direction, being coupledto a first RRAM cell of the first column of RRAM cells and a second RRAMcell of the second column of RRAM cells; and a source line extending inthe second direction, being coupled to the first column of RRAM cellsand the second column of RRAM cells, and being shared by the firstcolumn of RRAM cells and the second column of RRAM cells, the sourceline comprises: a first conductive line extending in the seconddirection, and being located on a first metal layer; a second conductiveline extending in the second direction, and being located on a secondmetal layer above the first metal layer, the first conductive line andthe second conductive line overlap drains of corresponding transistorsof corresponding RRAM cells of the first column of RRAM cells; and afirst set of vias between the first conductive line and the secondconductive line, and each via of the first set of vias being positionedabove where the first conductive line overlaps each drain of thecorresponding transistors of the corresponding RRAM cells of the firstcolumn of RRAM cells.
 16. The memory cell array of claim 15, wherein awidth of the first conductive line is substantially equal to a width ofthe second conductive line.
 17. The memory cell array of claim 15,wherein the word line comprises: a third conductive line extending inthe first direction, and being located on a third metal layer above thefirst metal layer and the second metal layer.
 18. The memory cell arrayof claim 17, wherein the first bit line or the second bit linecomprises: a fourth conductive line extending in the second direction,and being located on a fourth metal layer above the first metal layer,the second metal layer and the third metal layer; a fifth conductiveline extending in the second direction, and being located on a fifthmetal layer above the first metal layer, the second metal layer, thethird metal layer and the fourth metal layer; and a second set of viaselectrically coupled to the fourth conductive line and the fifthconductive line, and being located between the fourth conductive lineand the fifth conductive line.
 19. The memory cell array of claim 18,wherein each RRAM cell of the first column of RRAM cells or the secondcolumn of RRAM cells comprises: a resistance switching element coupledto the first bit line or the second bit line; and a switch coupledbetween the resistance switching element and the source line, andfurther coupled to the word line.
 20. The memory cell array of claim 15,wherein the first conductive line and the second conductive line furtheroverlap drains of corresponding transistors of corresponding RRAM cellsof the second column of RRAM cells; and the source line furthercomprises: a second set of vias between the first conductive line andthe second conductive line, and each via of the second set of vias beingpositioned above where the first conductive line overlaps each drain ofthe corresponding transistors of the corresponding RRAM cells of thesecond column of RRAM cells, the second set of vias being separated fromthe first set of vias in the first direction.